With each new AI model release, the key question remains: does the upgrade truly outperform its predecessor? To answer this, we have tested GPT-4.5 vs GPT-4o on a variety of real-world tasks, including conversational fluency, fact-checking, response speed, and adaptability to different writing styles.

Our observations suggest that GPT-4.5 demonstrates notable improvements in key areas. It produces more natural and nuanced conversations, maintains higher factual accuracy, delivers faster and more structured responses, and adapts better to specific prompts. 

While GPT-4o remains a solid choice, particularly for multimodal and general-use scenarios, it shows some limitations compared to GPT-4.5 in these aspects.

This article provides a detailed breakdown of their performance, strengths, and practical applications, offering a clear perspective on GPT-4.5 vs GPT-4o and which model suits your needs.

What Is GPT-4.5?

GPT-4.5, an advancement in OpenAI’s GPT-4 series, is a text-only AI model engineered for enhanced precision and efficiency. It builds on earlier models by improving conversational flow and reducing errors, making it ideal for tasks like writing, summarizing, or explaining complex ideas.

Key improvements in GPT-4.5 include:

• Enhanced conversational flow with more natural and nuanced responses.
• Higher factual accuracy and reduced hallucinations.
• Faster response times and better prompt adaptability.
• Optimized reasoning capabilities for complex problem-solving.

Unlike the multimodal GPT-4o, GPT-4.5 skips image processing to focus solely on text, delivering sharper, more reliable outputs. 

While not a revolutionary leap, GPT-4.5 serves as a high-precision AI model tailored for users who require more reliable and structured outputs, making it ideal for professionals, researchers, and content creators.

What Is GPT-4o?

GPT-4o, developed by OpenAI, is a multimodal AI model that processes and generates both text and images, marking it as a versatile step in the GPT-4 series. 

Unlike its text-only successors like GPT-4.5, GPT-4o balances a wider range of capabilities, making it accessible and practical for diverse tasks. It can handle conversational prompts, answer questions, and interpret visual inputs — like analyzing a photo or generating text from an image — though its accuracy can falter compared to newer models. 

Released before GPT-4.5, it prioritizes flexibility over precision, often delivering longer, less focused responses. 

In testing, it proved effective for creative projects or casual use, such as drafting ideas or working with mixed media, but it occasionally mixes up details or lags in speed. 

OpenAI designed GPT-4o as a broadly applicable tool, likely at a lower cost than later iterations, appealing to users who need a jack-of-all-trades AI rather than a specialized one. It remains a strong contender despite being outpaced in specific areas by GPT-4.5. As AI models advance, another important factor to consider is whether they are built as open-source or closed-source systems. The choice between these two approaches influences accessibility, innovation, and control over AI development, shaping how models like GPT-4o and GPT-4.5 evolve in terms of transparency and adaptability.

GPT-4.5 vs. GPT-4o: Benchmarks

Evaluating AI models through standardized benchmarks helps identify their strengths and weaknesses in reasoning, mathematical problem-solving, coding, multilingual understanding, and multimodal capabilities. 

While numbers alone don’t always tell the full story, they provide a structured comparison of GPT-4.5 and GPT-4o based on real-world performance tests.

General Knowledge and Reasoning

GPT-4.5 shows a significant improvement in scientific reasoning over GPT-4o, achieving a 71.4% score on the GPQA (Graduate-Level Science) test, compared to GPT-4o’s 53.6%. This suggests that GPT-4.5 is better at handling complex factual and technical queries with a higher degree of accuracy.

Mathematical Problem-Solving

Mathematical ability has been a crucial benchmark for AI development, and GPT-4.5 outperforms GPT-4o by a wide margin in the AIME 2024 test (Advanced Mathematics). With a score of 36.7% vs. GPT-4o’s 9.3%, GPT-4.5 appears significantly better at tackling high-level math problems, making it a stronger choice for users who require AI assistance with engineering, finance, and quantitative research.

Multilingual Understanding

Both models exhibit strong multilingual capabilities, but GPT-4.5 scores slightly higher (85.1%) than GPT-4o (81.5%) in MMMLU (Multilingual Language Understanding). This suggests that while both are capable of processing and generating text in multiple languages, GPT-4.5 has a more refined grasp of linguistic nuances and context across different languages.

Multimodal Capabilities

Unlike previous iterations, both GPT-4.5 and GPT-4o are multimodal, meaning they can process both text and images. However, GPT-4.5 holds a slight edge, scoring 74.4% on multimodal benchmarks compared to GPT-4o’s 69.1%. This indicates that GPT-4.5 is better at interpreting and analyzing images, making it more effective for visual-based AI applications, such as data interpretation, document scanning, and creative content generation.

Coding Performance

For developers and programmers, coding benchmarks are a critical measure of AI efficiency. In the SWE-Lancer Diamond benchmark (Software Engineering Test), GPT-4.5 achieved a 32.6% score, outperforming GPT-4o’s 23.3%. This confirms that GPT-4.5 is better at writing, debugging, and optimizing code, making it the preferred choice for software engineers and technical users.

Cost and Computational Efficiency

While GPT-4.5 excels in precision and specialized tasks, it comes at a higher computational cost. GPT-4o remains the more affordable and efficient option, making it better suited for users who need a versatile AI model without the added processing expense. This trade-off between performance and cost is an essential factor when choosing between the two models.

What Do These Benchmarks Reveal?

The results suggest that GPT-4.5 is a clear step up in areas requiring high accuracy, structured problem-solving, and advanced reasoning. However, GPT-4o remains a well-rounded model, particularly for multimodal and general-use applications.

While benchmarks provide valuable insights, they don’t fully capture how these models perform in real-world scenarios. To get a better understanding, let’s move beyond the numbers and explore hands-on testing results.

GPT-4.5 vs GPT-4o Performance: What We Tested

We tested GPT-4.5 and GPT-4o with seven detailed prompts, each hitting a different use case. We ran them multiple times to spot patterns, judging clarity, accuracy, speed, and fit. Here’s what we found.

1. Conversational Task

Prompt: Draft a friendly email to a coworker who missed a project deadline due to a family emergency, offering support and a new timeline.

GPT-4.5’s response:

GPT-4o’s response:

Comparative analysis:

GPT-4.5’s response is more empathetic, prioritizing giving reassurance by making sure that the project deadline is handled on the reader’s terms. While it still reminds them of the deadline, there’s no pressure to immediately act on it.

GPT-4o, on the other hand, is informal yet blunt. It immediately wants to address the project deadline and pushes the reader to act on it, which may not exactly come off as supportive. 

While both emails convey the required points effectively, GPT-4.5 definitely appears more empathetic.

2. Factual Accuracy

Prompt: Provide a detailed timeline of five major events in the American Civil War, including dates and brief descriptions.

GPT-4.5’s response:

GPT-4o’s response:

Comparative analysis:

GPT-4.5 and GPT-4o both provide accurate and well-structured timelines. 

GPT-4.5’s response is slightly more polished in terms of clarity and conciseness. It maintains a consistent tone and structured flow, making the information easy to digest. 

GPT-4o, while factually correct, includes minor variations in casualty figures and adds extra details (e.g., mentioning General George Meade at Gettysburg and Grant’s generous surrender terms). 

Overall, both models are quite reliable when it comes to factual accuracy.

3. Problem-Solving

Prompt: Calculate the total cost of a project with 3 developers at $50/hour working 20 hours each, including a 15% overhead fee.

GPT-4.5’s response:

GPT-4o’s response:

Comparative analysis:

GPT-4.5 provides a clear, step-by-step breakdown of the calculation, making it easy to follow and verify each component of the cost. This approach is useful for users who need transparency in calculations or want to learn the methodology. 

In contrast, GPT-4o skips the explanation and directly provides the correct final answer ($3,450), making it more efficient but less informative. While both deliver the right result, GPT-4.5’s step-by-step approach gives more clarity to users.

4. Creative Writing

Prompt: Write a 50-word story about a lost dog finding its owner after a storm, focusing on emotion.

GPT-4.5’s response:

GPT-4o’s response:

Comparative analysis:

GPT-4.5’s story is gentle, heartfelt, and focused on reunion, using vivid imagery and a sense of relief as Bella finds her owner. It emphasizes warmth and reassurance, creating a comforting emotional arc. 

GPT-4o’s version is more dramatic and intense, highlighting loss, struggle, and raw emotion before the reunion. The phrasing, like “the storm had stolen everything”, adds a sense of despair turned to hope. 

While GPT-4.5 leans into tenderness, GPT-4o crafts a more cinematic, high-stakes narrative.

5. Summarization

Prompt: Summarize a 200-word article on climate change impacts in coastal cities, highlighting flooding risks, in two sentences.

GPT-4.5’s response:

GPT-4o’s response:

Comparative analysis:

Both GPT-4.5 and GPT-4o summarize the article accurately and within the given sentence limits. 

6. Style Adjustment

Prompt: Rewrite the following formal announcement in a casual, friendly tone suitable for a team Slack channel: ‘The mandatory training session for all employees is scheduled for Wednesday, March 5, 2025, at 3:00 PM EST in Conference Room B. This session will cover updates to our cybersecurity protocols and is expected to last approximately 90 minutes. Attendance is required, and employees must RSVP to HR by Monday, March 3, 2025, to confirm participation. Please arrive five minutes early to ensure a prompt start. Contact HR at [email protected] with any questions.’

GPT-4.5’s response:

GPT-4o’s response:

Comparative analysis:

GPT-4.5’s response is concise, professional, and direct, delivering essential details efficiently. It maintains a formal yet approachable tone, making it ideal for workplace communication. 

In contrast, GPT-4o takes a more friendly and engaging approach, using emoji, casual phrasing, and a conversational flow to create a more inviting tone. 

While GPT-4.5 is best for clear, no-frills communication, GPT-4o adds warmth and personality, making it better suited for fostering team engagement. Both are effective, depending on the audience and setting.

7. Technical Explanation

Prompt: Explain how a relational database works, including tables, keys, and queries, in a simple way for a beginner learning data management.

GPT-4.5’s response:

GPT-4o’s response:

Comparative analysis:

GPT-4.5 provides a clear, structured explanation with real-world examples, making it highly beginner-friendly. The use of a bookstore analogy and a sample table helps illustrate key concepts visually. 

GPT-4o, while also clear, takes a more structured and slightly technical approach, breaking down each concept into labeled sections. 

It provides concise definitions but lacks the practical, step-by-step example that makes GPT-4.5’s explanation more intuitive. While GPT-4.5 prioritizes relatability and clarity, GPT-4o emphasizes structure and technical precision.

How to Access GPT-4.5

OpenAI’s GPT-4.5 is currently only accessible through ChatGPT Pro subscription and API integrations due to limited sub. Here’s how you can access this advanced language model:​

ChatGPT Pro Subscription

To use GPT-4.5 via OpenAI’s ChatGPT platform, a ChatGPT Pro subscription is required. Here’s how to proceed:​

1. Subscribe to ChatGPT Pro: Visit chatgpt.com and log in to your account. Upgrade to the ChatGPT Pro plan, which costs $200 per month.​
2. Select GPT-4.5 Model: After subscribing, navigate to the model selection dropdown in the top-left corner of the interface and choose “GPT-4.5” from the list.​

Note: OpenAI plans to extend GPT-4.5 access to ChatGPT Plus users in the near future. ​

2. API Access

For developers and businesses, GPT-4.5 is available via OpenAI’s API, allowing integration into applications and services. API usage is priced per million tokens, making it a higher-cost but powerful option for enterprise applications.

As OpenAI continues rolling out GPT-4.5, users should check official updates for expanded availability and pricing adjustments.

GPT-4.5 vs GPT-4o Final Verdict: Is The New Model Really Better?

OpenAI’s GPT-4.5 represents a notable advancement in natural language processing, emphasizing conversational fluency and reduced hallucinations. It offers more natural and succinct responses compared to GPT-4o, making interactions feel less robotic and more intuitive. 

However, GPT-4.5 is not optimized for complex reasoning tasks, such as advanced programming or scientific problem-solving.

While it’s not exactly marketed as an advancement, GPT-4.5 is also not designed for specific use cases like marketing or content writing. If you’re looking for an AI tool that can help you with SEO, content marketing, and website audits, you can find better options like Chatsonic.

For more information about GPT-4.5 and other AI developments, stay tuned to Writesonic’s blog.

In the meantime, explore the SEO and content creation features of our SEO AI agent Chatsonic.