> For example, pushes exist in the API, but don't really within git.

`git push`?

I was unclear, sorry. You can't tell what pushes have occurred in the past from a git repo, but you can with the GitHub API.

I don't get it... The API is built on top of `git`!

GitHub has lots of things that Git doesn't have. As well as recording pushes and making them available over the API, it records fork information, has concepts of users and organizations which dont exist in git, has pull requests, comments, and post-commit code review, an issue tracker, etc, etc, etc.