A concrete example: I was doing shader programming with Sonnet 3.5 and ran into a visual bug. Sonnet asked me to add four debugging modes, cycle through each one, and describe what I saw for each one. With one more prompt, it resolved the issue. In my experience, GPT-4o has never bothered proposing debug modes and just produced more buggy code.
For non-trivial coding, Sonnet 3.5 was miles above anything else, and I didn't even have to try hard.