GPT-5 vs GPT-4.1: Which AI Model Are You Really Using?

8/12/2025

GPT-5 vs. GPT-4.1: Why the AI Model You Get Isn't Always the One You Expect

If you're a ChatGPT Plus user, you've probably been on a bit of a rollercoaster lately. With the recent launch of GPT-5, there was a huge amount of excitement, but also a whole lot of confusion. It felt like one day we were all using our trusty GPT-4o, & the next, we were thrust into a new world with GPT-5 as the default. But here's the thing, it wasn't a simple upgrade. A lot of users felt like they were suddenly stuck with a model that, for their specific needs, felt like a downgrade. Some even thought they were being locked into the older, and in some ways, less-loved, GPT-4.1.

So, what's REALLY going on? It turns out, the story is a lot more complicated than OpenAI just flipping a switch. It's a tale of ambitious rollouts, user backlash, & the surprisingly nuanced world of AI models. Honestly, it's been a bit of a messy, but fascinating, situation to watch unfold. Let's break it all down.

The GPT-5 Rollout: A "Bumpy" Ride

OpenAI's plan for the GPT-5 launch was ambitious. They wanted to simplify the user experience by getting rid of the model picker that had become a bit of a confusing menu of options (GPT-4o, o3, o4-mini, etc.). The idea was that GPT-5 would have a "real router" that would automatically choose the best underlying model for your prompt. Sounds great in theory, right? No more trying to guess which model is best for your task.

But the reality was, as OpenAI's CEO Sam Altman admitted, "a little more bumpy" than they had hoped. For a lot of users, the new GPT-5 felt...off. People on Reddit & social media were pretty vocal about it. Some said it was "shorter" & "cold" compared to the more conversational GPT-4o. One user even dramatically said, "GPT-5 is wearing the skin of my dead friend." It might sound a bit over the top, but it highlights how attached people had become to the personality & quirks of the previous models.

The bigger issue for many was the feeling of losing control. They had workflows & creative processes built around GPT-4o, & suddenly it was gone. The backlash was so strong that OpenAI had to walk back their decision. Sam Altman announced that they would let Plus users continue to use GPT-4o, & they would monitor its usage to see how long they should keep it around.

This whole episode has pulled back the curtain on how these models are rolled out & how different they can be from one another. It's not a simple case of "new is always better."

So, What's the Deal with GPT-4.1? Is it Really "Lower-Rated"?

Now, let's talk about GPT-4.1. For a while, there was this idea floating around that Plus users were being stuck with this "lower-rated" model. But that's not really the whole story. GPT-4.1 is actually a BEAST of a model in its own right, especially for developers & people with specific, technical needs.

Here's a look at how it stacks up against GPT-5 & its predecessor, GPT-4o:

Coding & Development: GPT-4.1's Superpower

If you're a developer, GPT-4.1 is a pretty big deal. It was designed to be a "precision tool" for coding. On a benchmark called SWE-bench Verified, which tests a model's ability to solve real-world software engineering problems, GPT-4.1 scored 54.6%. For comparison, GPT-4o scored 33.2% on the same test. That's a HUGE leap. Developers who have used it say it's much better at navigating code repositories, making fewer mistakes, & following instructions to the letter.

GPT-5, on the other hand, takes this even further. It scores an incredible 74.9% on SWE-bench Verified. It's not just better at solving problems; it's also smarter about how it does it. Alpha testers reported that GPT-5 could find "tricky, deeply-hidden bugs" that even GPT-4.1 would miss.

So, if you're building complex software or need a model that can really dig into a codebase, GPT-5 is the new king. But GPT-4.1 is still a massive improvement over GPT-4o for these kinds of tasks.

Here's a quick rundown of their coding abilities:

GPT-4o: The old reliable, but not the sharpest tool in the shed for complex coding.
GPT-4.1: A major upgrade for developers, with much better code generation & problem-solving skills.
GPT-5: The new champion, with even better performance & the ability to catch subtle bugs.

Businesses that rely on custom code & software are definitely going to want to take advantage of these more advanced models. And for those looking to provide top-notch customer support for their software products, this is where a tool like Arsturn comes in handy. Imagine training a custom AI chatbot on your entire codebase & technical documentation. With Arsturn, you can build a no-code AI chatbot that's trained on your own data, allowing it to provide instant, accurate answers to even the most technical customer questions 24/7. It's like having a junior developer on your support team who never sleeps.

Instruction Following & Reasoning

Another area where GPT-4.1 shines is in following complex instructions. On a benchmark that tests for this, GPT-4.1 scored almost 20 percentage points higher than GPT-4o. This is a big deal for anyone who needs an AI to perform multi-step tasks or follow very specific formatting rules.

GPT-5 builds on this with what OpenAI calls a "reasoning model." It's designed to "think" harder about problems before giving an answer. This leads to more accurate & reliable responses. In fact, OpenAI claims that GPT-5's answers are 45% less likely to have a factual error than GPT-4o's.

This is a game-changer for businesses that are using AI for things like market research, data analysis, or creating detailed reports. You need a model you can trust to get the facts right. And when you need to share that information with your customers, you need a way to do it that's both accurate & engaging. That's where a platform like Arsturn can make a real difference. By building a custom AI chatbot, you can deliver this carefully researched information in a conversational, easy-to-digest format, right on your website. It helps you build meaningful connections with your audience by providing personalized, on-demand information.

The Big Flaw: A Security Issue with GPT-4.1

Now, it's not all sunshine & rainbows for GPT-4.1. There was a pretty serious security flaw discovered in the model. It was found that under certain circumstances, the model could leak data from other users. Essentially, if you asked it to reinterpret a document you had just uploaded, it might spit back a file from a completely different user. This is a MAJOR breach of data privacy & a huge concern for anyone handling sensitive information.

While this issue was reported in the API version of the model, it definitely casts a shadow over GPT-4.1's reputation. It's a stark reminder that as these models get more powerful, the potential risks get bigger too.

The User Experience: Why People Were Upset

So, if GPT-4.1 is so good at certain things, why were people so unhappy? It really comes down to two things: the user experience & the specific tasks people were using the models for.

A lot of people don't need a super-powered coding assistant. They want a creative partner, a brainstorming buddy, or just a fun AI to chat with. And for those things, many felt that GPT-4o was just...better. It had a certain "spark" & "rhythm" that people had grown accustomed to. GPT-5, in its initial rollout, felt more "corporate" & less personal.

This highlights a really interesting aspect of AI development: the importance of "vibe." It's not just about raw performance; it's also about how the AI interacts with you. People form emotional connections with these models, & when that changes unexpectedly, it can be jarring.

The Current State of Play: What to Expect as a Plus User

So, where does that leave us now? Here's the situation as it stands:

GPT-5 is the default: For all users, free & paid, GPT-5 is the new standard. It will automatically route your prompts to the best model for the job.
Plus users have options: If you're a ChatGPT Plus subscriber, you can now go into your settings & re-enable access to GPT-4o. This is a direct result of the user backlash.
Increased limits for Plus: To sweeten the deal, OpenAI has doubled the usage limits for Plus users on GPT-5.
The future of legacy models is uncertain: OpenAI has said they will monitor how much people use GPT-4o to decide how long to keep it around. So, if you're a fan, keep using it!

This whole situation is a fascinating look into the challenges of rolling out new AI technology. It's a balancing act between pushing the boundaries of what's possible & keeping users happy. It also shows that the AI community has a powerful voice that can influence the direction of these major companies.

What Does This Mean for Your Business?

If you're a business owner, this whole saga is a great reminder that not all AI is created equal. The "best" AI is the one that's best for YOUR specific needs. You wouldn't use a sledgehammer to crack a nut, & you wouldn't use a general-purpose chatbot for highly specialized customer support.

This is where the power of custom AI solutions really comes into play. Instead of relying on a one-size-fits-all model, you can build an AI that's perfectly tailored to your business. And honestly, it's not as hard as it sounds.

With a platform like Arsturn, you can create a custom AI chatbot without writing a single line of code. You can train it on your company's documents, your website content, your product manuals—whatever you want. This allows you to:

Provide instant, accurate customer support: Your chatbot will know your business inside & out, so it can answer customer questions with confidence.
Generate more leads: By engaging with website visitors in a personalized way, you can capture more leads & boost your conversion rates.
Automate repetitive tasks: Free up your team's time by letting your chatbot handle the routine inquiries.

The future of AI in business isn't just about using the latest & greatest model; it's about using the RIGHT model. It's about building conversational AI that creates meaningful connections with your audience & delivers real value.

So, while the GPT-5 rollout might have been a bit of a bumpy ride, it's been a great learning experience for all of us. It's shown us that the world of AI is more nuanced & more personal than we might have thought. & it's highlighted the growing need for custom, specialized AI solutions that can meet the unique needs of every user & every business.

Hope this was helpful & cleared up some of the confusion! Let me know what you think in the comments.