There is certainly a difference, however Anthropic did really well with 3.5 - far, far better than any other provider could do, so the steps from there been more incremental while other providers have been playing catch up (for example Google's Gemini 2.5 Pro is really their first model that's actually useful for coding in any way).

I can tell the difference between those versions of Claude quite easily. Not 10x better each version, but each is more capable and the errors are fewer.

You won’t find perfection anywhere

errors are all over the place no matter what. the question is how predictable they are, and if they can be spotted as they show up.

the best bugs are the ones that arent found for 5 years