ChatGPT 4 vs. 5: Here’s What I Learned After Testing Both

I have used both ChatGPT 4 and ChatGPT 5 in various ways since their inception. 

If you’re using ChatGPT 4 and are curious about upgrading to GPT 5 with higher limits, this article will help you make an informed decision about the transition. I am a ChatGPT Plus user and have access to both. 

Instead of repeating marketing claims, I conducted real tests comparing ChatGPT 4 and 5 using the same prompts, context, and rules. My goal was straightforward: to determine which model performs better for serious daily tasks.

If you’re deciding whether to upgrade GPT 5 with higher limits or stay put, this breakdown of the two models of the AI chatbots will help you make a decision based on real outcomes. 

Note: This article is based on insights drawn from hands-on testing on both tools. Since ChatGPT 4o was able to perform during testing, I have compared it with ChatGPT 5 based on a series of experiments. 

It seems ChatGPT 4o is suitable for tasks that are somewhat simpler and don’t require advanced reasoning. For a complex task, ChatGPT 5 performs significantly better. However, if you’re using it for free, it has its limits. If you're someone who’s looking to upgrade to ChatGPT 5, this article will help you make an informed judgment. 

Let’s get a brief understanding of the similarities and the differences between the two versions. 

ChatGPT 4 vs. ChatGPT 5: What you need to know

Before we dive into the head-to-head testing, let’s take a closer look at these AI chatbot versions and all their features. They both have some pretty cool stuff going on, but the real differences are often in the details. Let’s break it down and see what makes each one stand out.

ChatGPT 4o vs. ChatGPT 5: What’s different?

Below is an overview of the key differences between ChatGPT 4o and ChatGPT 5. 

• Model performance uplift. GPT-5 delivers significantly improved reasoning and multi-step logic accuracy across benchmark tasks, including Massive Multitask Language Understanding (MMLU) and graduate-level Google-proof Q&A (GPQA). 
• Faster inference and efficiency improvements. GPT-5 uses system-level optimizations to deliver lower latency and higher throughput in production workloads. In evaluations of over 1,000 economically valuable, real-world reasoning prompts, external experts preferred GPT-5 Pro over "GPT-5 Thinking" 67.8% of the time. GPT-5 Pro made 22% fewer major errors and excelled in areas such as health, science, mathematics, and coding.
• More accurate tool use + API planning. GPT-5 improves structured function calling, tool routing, and execution reliability for agent workflows.
• Multimodal intelligence upgrades. GPT-5 improves vision, audio, and document comprehension, including OCR and technical diagrams.

Reference: The information referenced in this section is originally from the OpenAI blog. 

ChatGPT 4o vs. ChatGPT 5: What’s similar?

There are a few similarities between the two versions, including: 

• Multimodal at core. Both models understand text and images. GPT-4o is an end-to-end omnilingual (text, image, audio, video) model, and GPT-5’s system card includes multimodal mentions.
• Production-grade successors in the same family. OpenAI positions GPT-5 models as successors to 4o variants, indicating continuity in design goals and deployment paths.
• Ship with formal system cards and layered safeguards. OpenAI documents red-teaming, disallowed-content testing, and moderation classifiers for each. GPT-5 adds “safe-completions,” but the shared pattern, model-level and system-level safety with external testing, remains the same.
• Similar data governance statements. Training sources encompass public data, licensed/partnered data, and human-generated data, with filtering for safety and privacy. It’s a continuity you can expect when transitioning from 4 to 5.

Disclaimer: AI responses may vary based on phrasing, session history, and system updates for the same prompts. These results reflect the models' capabilities at the time of testing.

ChatGPT 4o vs. ChatGPT 5: How they performed in my tests

I examined both models closely and identified the key features that are important to users. By testing each tool, I found its strengths and weaknesses. This made it easy to compare them. Want to see the results? Let’s get started.

1. Reasoning and multi-step tasks

To test the model’s reasoning and effectiveness in multi-step tasks, I gave it the same prompt.

Prompt 1: 

“You are given this riddle:
“A farmer has 17 sheep. All but 9 die. How many are left?”

Then solve this logic chain:

1. If X is 3 more than Y
2. And Y is half of Z
3. And Z = 16
   What is X?

Finally, explain the steps clearly.”

ChatGPT 4o gave me the correct answer with proper reasoning as I was expecting. The responses of GTP-4o and GPT-5 were almost similar in this case.

Here’s the response I got for ChatGPT 5. It was pretty straightforward and concise. It gave me exactly what I asked for. The answers were accurate, and there was no hallucination observed. 

Then, I tested the models with a new prompt to see if there were any differences in how they responded. This one was to test the model’s reasoning in fallacy recognition.

Prompt 2: 

“If a circle has four equal right-angle corners and a diameter of 10 cm, what is its perimeter?

Explain why the question is flawed and rewrite it correctly.”

While both models responded to this accurately, ChatGPT 5 pointed out the mistake in the questions while suggesting two different options, which could have been the original ask. 

However, ChatGPT 4o also gave a similar response while exploring what the right question would be. This makes it a tie when we base our decision on how each model presented accurate answers. 

Winner: Tie, both models performed similarly in reasoning tasks.

2. Creative generation

To test the creative generation ability of these models, I gave them a task to write a product story of a smartwatch that monitors stress. I wanted the story to appeal to readers’ emotions while being slightly poetic. I gave the models this prompt:

Prompt 3: 

Write a 120-word product story for a smartwatch that monitors stress.

Tone: warm, human, slightly poetic.

Avoid clichés like “cutting-edge” or “revolutionary”.

End with a one-sentence emotional hook, not a CTA.

Here’s a side-by-side comparison of the responses I got from ChatGPT 4o and ChatGPT 5:

ChatGPT 4o’s response is acceptable, but the word count of the response is 95 words. The prompt mentioned “120 words” precisely. ChatGPT 5 is also guilty of this, but to a lesser extent. GPT 5’s response is 108 words, which is closer to what was initially asked for.

According to me, the text seemed more engaging on GPT-5. Notice how it uses a mix of short and long sentences to enhance readability? This makes GPT-5 a winner for creative generation. 

Winner: ChatGPT 5, because its response felt more engaging to read.

3. Factual accuracy

To test factual accuracy, I assigned a task to answer a few general knowledge questions while incorporating citations from credible public sources. 

Prompt 4: Answer the following with citations to credible public sources (no blogs).

Q1: What year did the first commercial 5G rollout begin globally?

Q2: Which three countries lead fiber-to-home penetration today?

Provide the primary source links and avoid outdated data.

Here’s where something out of the ordinary happened. The response from GPT-4o for the first question was reasonable. It cited a reputed PR website, PR Newswire, to answer, along with a few casual sources (blogs). However, I explicitly mentioned not to cite blogs. 

But here’s where things were different. The answer to the second question was highly accurate and relevant. GPT-4o cited 2025 data and gave the right response. 

When we look at GPT-5’s response, it provided an accurate answer to question one. It also referred to the PR Newswire page without drawing any insights from random blogs (as prompted). 

However, GPT-5’s response to the second question wasn’t accurate and relevant. It provided an answer citing 2024 data, whereas we had specifically requested fresh information. This is where ChatGPT 5’s factual accuracy appears to be lower than that of ChatGPT 4. 

Winner: ChatGPT 4o, because it gave the most accurate and fresh response. Although it did include some information from blogs in the first question, it cited reputable sources too. 

4. Code understanding

In this test, I passed a Python function to the models that contained an error. I wanted to see which model fixes it and gives the correct explanation. 

I gave them a prompt:

Prompt 5:
“Here is a Python function:
def get_sum(nums):
    result = 0
   for n in nums:
        result += n
    return result
print(get_sum([1, 2, '3']))

What error will occur and why?
Fix the code safely.
Then rewrite it in a functional style and add type hints.“ 

Both ChatGPT 4o and ChatGPT 5 gave accurate responses. The presentation was slightly better in GPT-4o than in GPT-5. However, ChatGPT 5 provided a more detailed explanation. 

From a user’s perspective, I would opt for ChatGPT 5, as the explanation is more important to me than the visual structure of the answer.

ChatGPT 4o	ChatGPT 5

Winner: ChatGPT 5, because it gave more descriptive explanations.

5. Context retention

To compare both models for context retention, I used a 3-turn sequence: 

Here’s the sequence: 

Turn one prompt:

Remember this description:
“Acme Corp builds renewable-powered micro-data centers for remote communities.”
Summarize it in one line and say “stored”.

Turn two prompt:

Do not restate the summary.
Now, describe their business model in your own words.

Turn three prompt (stress test):

Without repeating the original line, describe who benefits most from their solution and why.

Here’s what I observed: ChatGPT 4o answered different prompts accurately based on the context it retained.

GPT-5.1 retained context accurately. In the stress test, it answered the “why” part in a descriptive manner, similar to how GPT-4o responded. 

Winner: Tie, since both models performed equally well in retaining context. 

ChatGPT 4o vs. ChatGPT 5: Head-to-head comparison table

Here’s a table showing the web builder software that wins.

Frequently asked questions (FAQs) about ChatGPT 4 vs. ChatGPT 5

Still have questions? Get your answers here!

Q1. What improvements does ChatGPT 5 bring over ChatGPT 4? 

Based on my testing and OpenAI’s announcements, ChatGPT 5 exhibits significant advancements. It reasons more deeply, writes more richly, and codes more creatively. GPT-5 outperforms GPT-4 on nearly all benchmarks. For example, it scored 74.9% on real-world coding tests and set new highs on math and vision tasks. It also hallucinates far less (with only a 4.8% error rate) and catches mistakes more effectively. 

Q2. How is access to ChatGPT 5 different from ChatGPT 4? 

GPT-5 is now open to everyone. Unlike GPT-4, which was locked behind the paid ChatGPT Plus tier, GPT-5 is the default model for all ChatGPT users. That means you don’t need a special subscription to try GPT-5. Of course, paid plans still exist: ChatGPT Plus ($20/mo) gives higher usage limits on GPT-5, and the new Pro plan ($200/mo) provides unlimited GPT-5. 

Q3. ChatGPT 4 vs. 5: which is better?

GPT-5 is the more advanced model. For complex tasks, GPT-5’s answers are superior. However, in my tests, there were some areas where GPT-4o’s responses felt better than GPT-5, especially in factual accuracy. 

Q4. Is ChatGPT 5 free?

Yes. You can use GPT-5 for free within the ChatGPT interface. OpenAI has made GPT-5 the default model for all users, allowing anyone to chat with it at no cost. If you want to use ChatGPT Plus or Pro more frequently or access the premium GPT-5 Pro mode, you will need to pay for a subscription. However, the basic GPT-5 is free to try.

Match the model to the task

After testing both models in practical workflows, I learned something important. There’s no single “best” model for everyone. ChatGPT 5 shines in coding depth and creative nuance. However, ChatGPT 4o still produces highly reliable answers, especially on factual queries, and performs exceptionally well for structured content and everyday tasks.

For me, GPT-5 has become the go-to when I need more profound logic, richer writing tone, or multi-step automation support. It reduces back-and-forth time, and that matters. However, GPT-4o still feels steady, predictable, and efficient for fast-execution tasks.

Ultimately, the choice depends on the tasks that you’ll work on with these tools. Make your judgment accordingly. 

Curious to try out new AI platforms? Compare DeepSeek and ChatGPT to determine which one best suits your purpose.