Hello! 😃

We are currently in the golden age of AI for automatic programming, known as "AI pair coding"!

 

Various editors and chats are incredibly helpful for tasks such as:

• Writing programs from scratch
• Reading source code and improving it
• Answering technical questions

 

Now, there are many types of AI partners available.

Among them, the two biggest names that assist us during programming (coding) are:

Anthropic's Claude and OpenAI's GPT (ChatGPT).

 

While I'll leave the detailed differences to official documentation and other blogs, here I will explain how they differ when used in actual work.

 

To put it concisely:

 

• GPT series = Faster, but often tries to improve things in a completely different direction than intended.
• Claude series = Takes more time to process, but has a higher chance of correctly understanding the intent.

 

Especially, the GPT series tends to confidently state things that are completely wrong (e.g., confidently claiming "This will work perfectly" in bold, even though it hasn't solved the problem at all 😆).

Therefore, it can be quite risky for non-engineers who can't read code to use it as a partner for pair coding.

 

Furthermore, GPT also has significant differences in quirks between agents, requiring care from the engineer's side when using them.

For example, it's like this 💭

 

• GPT5.3-Codex
  = There's a notable risk that the code will become more complex in a way that doesn't solve the requested task, a fair percentage of the time.
  ≒ Imagine a mid-level engineer with highly fluctuating performance.
  
• GPT4.1
  = If you request it well, it makes correct modifications very quickly, so the trick is to make careful requests.
  ≒ Imagine an excellent junior engineer who tirelessly awaits instructions.

 

So, if you are using it for work and have a choice of models, as of March 2026,

you will likely experience fewer reworks by choosing Claude Haiku, Claude Sonnet, or Claude Opus

than GPT-5.3-codex or GPT-5.4.

 

I hope this information is helpful!

 

Bonus

Incidentally, Claude's responses can be concise and sometimes a bit cold 😆

• Claude for those who prefer brief conversations
• GPT for those who prefer to be treated courteously

There's also this distinction in usage 👌