In the past, I might have said that there were some major similarities, but not so much now. The issue that I see with AUR is that each one is really independen

In the past, I might have said that there were some major similarities, but not so much now. The issue that I see with AUR is that each one is really independent and there isn't much of an assurance as to how well updated it would be. In the past, RPMFusion was also too slow to update for me, though, and I would frequently deal with update failures because of it. But that changed a few releases back. I literally just updated from Fedora 26->27 and all of the RPMFusion packages were automatically upgraded along with it. I have also found that the repo maintainenance is exceptional at this point. I think that the Fedora equivalent of AUR is probably COPR, but COPR probably isn't as good as AUR overall.