Both come with a IssueTracker (for bugs, feature requests, ...), a Wiki (for documentation), simple user management, and webhooks for automated build platforms.
You can do things like adding an issue-id into a commit statement which displays your commit in the issue ticket for others to reproduce what exactly was changed to fix a bug or implement a new feature. This can be super helpful when someone wants to extend a feature. Or reproduce why something isn't working any more, and fixing it instead of reverting the code and reintroducing a bug that was fixed (We had exactly such a problem of a reoccurring bug because two dev's didn't understand each others commits)
I prefer using GitLab for my company and private projects, since Microsoft has acquired GitHub. For public projects I prefer GitHub because the user community is larger.
GitLab also comes with extensive project management and DevOps support, and can run on your own infrastructure.
You should really check GitLab out again if the last time you used it / upgraded it was one year or so ago.