[MrJohz]

They're not quite the same thing as named branches in Git. In jj, a branch is a chain of commits. This chain of commits cannot be named. It's possible to create a bookmark, which is a name for a particular commit, and it's possible to use that bookmark to refer to a branch of commits (e.g. jj rebase's -b flag), but this is different from naming a branch like you would in git.

This is a subtle difference, and most of the time it doesn't matter at all, but in this case there is a difference between how bookmarks work in jj, and how branches work in git.