Github Copilot Chat is in beta and is marketed as a separate product. I suspect it is using a later generation (and better) underlying model. I used it many months ago, and I agree it is much better than vanilla Github Copilot. I haven't done a careful comparison to GPT-4, however. As you point out, the integration with the IDE does save a lot of time. Developers should definitely try it out.

https://docs.github.com/en/copilot/github-copilot-chat/about...