There's a difference in quality, though. IntelliSense was never meant to be more than autocomplete or suggestions (function names, variables names, etc.), i.e. the typing out and memorizing API calls and function signatures part. LLMs in the context of programming are tools that aim to replace the thinking part. Big difference.

I don't need to remember all functions and their signatures for APIs I rarely use - it's fine if a tool like IntelliSense (or an ol' LSP really) acts like a handy cheat sheet for these. Having a machine auto-implement entire programs or significant parts of them, is on another level entirely.