GPT-4.5 vs GPT-4: What’s the Difference?

If you’ve been keeping an eye on the evolution of AI, you’ve probably heard the buzz around GPT 4.5, OpenAI’s latest leap forward (as of April 2025).

So, what’s the real deal?

To put it simply, OpenAI’s GPT 4.5 is an optimized version of GPT-4. It makes GPT-4 more intuitive, faster, emotionally intelligent, has a broader context window, and is more suited for day-to-day interactions.

In this article, we’ll break down the key differences between GPT-4.5 vs GPT-4 and how these model architecture tweaks make a tangible impact on performance. Read on!

What Is GPT-4.5?

GPT‑4.5 is OpenAI’s latest and strongest ChatGPT model, built as a research preview that pushes the limits of unsupervised learning rather than reasoning (we’ll get into that soon).

OpenAI has released it for developers and Pro users so far.

It is not a complete overhaul like GPT-5 would be. And it’s not a “turbo GPT-4” either.

Instead, GPT 4.5 represents a fundamental shift in how language models learn: by scaling compute and architecture to supercharge their ability to connect concepts and generate insights without necessarily “thinking” in a human-like chain-of-thought style.

Instead, GPT-4.5 can be called a knowledge-native model.

It doesn’t simulate deep reasoning the way OpenAI o1 or o3-mini do, but it has a massively improved sense of the world, more accurate and emotionally intelligent.

This is why GPT-4.5 feels more conversational and natural in its responses.

GPT-4.5 vs. GPT-4: What’s Improved?

GPT-4.5 is much more than a faster version of GPT-4. The upgrades are architectural and cognitive.

OpenAI GPT‑4.5 was trained with more compute and on more advanced infrastructure using Azure AI supercomputers.

It uses scalable techniques that extract rich training signals from smaller models to teach itself how humans think and feel without direct human supervision.

GPT‑4.5 excels at SimpleQA (OpenAI’s benchmark for answering factual, knowledge-based questions). 

It has been trained to understand nuance, subtext, tone, and context.

In head-to-head comparisons, humans prefer GPT 4.5 over GPT-4o for creative tasks and everyday help. 

Plus, its responses feel more intuitive and conversational, more like talking to a knowledgeable peer than querying a database.

Performance & Benchmark Highlights

Now, let’s talk about hard data.

Here are the two most important performance benchmarks that compare how GPT-4.5 performs in relation to the GPT-4. 

• Accuracy: GPT-4.5 scores 62.5% accuracy on fact-based questions, which is a significant improvement over GPT-4o’s 38.2%. It means that the GPT-4.5 is far less likely to provide incorrect information.

• Hallucination rate: GPT 4.5 is also much less likely to make up false information (i.e., hallucinate). It scores 37.1% on hallucination rate, compared to 61.8% in GPT-4o. The low hallucination rate makes it more reliable and better suited for tasks that demand factual integrity, like research or technical support.

GPT-4.5 Features & Capabilities

What can you actually do with GPT-4.5?

The model has some seriously cool capabilities that make it feel way more intuitive and helpful than previous versions.

GPT-4.5 has broader and deeper world knowledge compared to earlier models.

You can ask it about niche topics like obscure history or advanced scientific concepts and get a detailed, accurate answer. 

However, the core features of GPT 4.5 are not built to outdo models designed for deep reasoning.

You won’t see it topping the charts in coding or solving tough scientific problems. 

What OpenAI’s really done here is focus on making it smarter for day-to-day conversations, writing, and answering general knowledge questions.

If you’ve ever had a frustrating experience where GPT-4 didn’t quite get your question, GPT-4.5 does a much better job at contextualizing what you mean.

Apart from being more accurate, OpenAI GPT 4.5 is also better at creative tasks like writing, designing, coding, and brainstorming ideas.

One of the more subtle but game-changing features of GPT-4.5 is its understanding of emotional context.

If you’re having a tough day or need reassurance, GPT-4.5 can provide empathetic responses that are far more intuitive than GPT-4 or other models. 

It knows when to comfort, when to offer advice, when to keep things light, etc.

Is GPT-4.5 Multimodal?

This is a big question because GPT-4.5 is a step toward multimodal AI, but it’s not fully there just yet. 

Multimodal models are AI models that can process multiple modalities, like video, audio, text, and image, at the same time.

Here’s what GPT-4.5 can do:

• GPT-4.5 can handle image uploads for interpretation and analysis–charts, photos, diagrams, screenshots, you name it
• You can upload PDFs or spreadsheets to summarize or analyze them
• You can work with GPT-4.5 on writing, coding, or organizing tasks in real-time using the Canvas mode 

And here’s what GPT-4.5 can’t do yet:

• Right now, GPT-4.5 doesn’t support real-time voice interaction
• It can’t process video files or engage in live video calls
• It’s not quite at the point where it can seamlessly integrate video, images, and text together in real time, though that’s likely a goal for future versions

So, it’s safe to say that GPT-4.5 is not a multimodal.

Use Cases for GPT-4.5

The following are some real, practical ways how GPT-4.5 actually improves your day-to-day tasks:

1. Writing and Content Creation: GPT-4.5 is a professional editor and creative partner at your fingertips. Unlike earlier models, GPT-4.5 doesn’t just throw ideas at you and leave you to piece them together, it helps you build on what you’ve started based on the context of your work.

2. Creative Partner That Thinks with You: If you ever get stuck at the “What’s next?” moment, you can always come to GPT-4.5 for help. It helps you think outside the box and refine your thoughts toward new directions you may not have considered.

3. Conversational Customer Support: With GPT-4.5, you can create AI-driven support tools that feel intuitive and human. It understands the tone of a customer’s inquiry, given its high emotional intelligence, acknowledges their feelings, and provides a calm, empathetic solution.

4. Emotional Support and Mental Health: GPT-4.5, with its emotional intelligence, can help provide an initial layer of support for those dealing with stress or just needing someone to talk to. It doesn’t replace human therapists, of course, but it creates a bridge for people who do not otherwise reach out for help.

5. Education and Tutoring: Instead of just providing a dry explanation, GPT-4.5 breaks down the topic in a way that aligns with a struggling student’s understanding. It offers analogies and simplifies the concept until it clicks.

6. Research Assistant: GPT 4.5 helps you organize and synthesize data quickly. It can pull out key points from research papers and summarize findings to save you hours of work. 

How GPT-4.5 Fits Into OpenAI’s Model Timeline

OpenAI has come a long way into building AI language models.

It started with GPT-1 in 2018, a basic proof of concept model able to understand and generate coherent sentences. 

Next up was GPT-2, with 1.5 billion parameters, which could generate more coherent and contextually relevant text than GPT-1.

The major breakthrough with GPT-2 was that it could carry context over multiple sentences.

GPT-3 in 2020 was a revolution in AI.

It could understand complex prompts, write essays, summarize articles, generate creative content, and even write code. 

It was hundreds of times bigger than GPT-2 with 175 billion parameters, however, it lacked consistency in longer conversations and sometimes provided responses that were off-mark or nonsensical. In other words, it used to hallucinate a lot. 

By 2022, OpenAI released GPT-3.5, a refinement rather than a revolutionary step.

It wasn’t radically different in size, but it was more stable and powered the launch of ChatGPT.

GPT-4 in 2023 represented a massive step forward in terms of both size and capability.

With a context window of 32k tokens, it could understand and process much larger chunks of text. 

GPT-4 also made huge strides in reasoning and problem-solving, particularly in coding, mathematics, and scientific tasks.

After GPT-4, OpenAI introduced variants like GPT-4o-mini, o1, o3-mini, and o3-mini-high.

And here we are today with Chat GPT 4.5, which addresses some core limitations of GPT-4, especially in terms of emotional intelligence and language intuition.

Is GPT-4.5 AI Content Detectable?

GPT-4.5 output, while impressive and better reasoned than GTP-4, is indeed detectable by AI content detectors, especially if you use the AI detector of Undetectable AI.

We put the text output generated by GPT 4.5 to check if it was detectable by Undetectable AI Detector despite its attempts at using human-like, conversational tone.

Undetectable AI evaluates the subtle patterns that distinguish human writing from machine-generated text.

It analyzes the tone of the text and the predictable flow of ideas that AI exhibits in its responses. 

Our test found that GPT-4.5 content was detectable using Undetectable AI. 

However, when you’re working with GPT-4.5-generated content and want it to feel a little less, well, AI, the AI Humanizer option is a quick fix.

It rearranges the sentence structure to make the flow of ideas feel less linear and adds a bit of that natural “thinking out loud” vibe that humans often have in their writing.

See our AI Detector and Humanizer in action—just use the widget below!

FAQs About GPT-4.5

Final Thoughts: Is GPT-4.5 Worth It?

ChatGPT 4.5 is a solid upgrade for those who value natural, engaging conversations and emotional nuance.

That said, if you need heavy reasoning capabilities or precise coding assistance, o3-mini still outperforms GPT 4.5 in structured problem-solving. GPT-4.5 is definitely worth considering only if your focus is thoughtful responses and better handling of emotional tone.

The content generated by GPT-4.5 can be detected using Undetectable AI.

The tool helps you assess whether your text holds up against AI detection and provides an inbuilt Humanizer that makes your text pass the test of human-like quality. 

Try it today to ensure your content remains undetectable and true to human writing!