ProtonPlus makes managing Proton versions on Linux, SteamOS and Steam Deck simple

Someone is already preparing an angry comment on how it should be written in Rust instead.

I've used both and found ProtonPlus to be better for my needs. It has way more proton and wine versions available. They also added the feature for steam games to select their proton version from the client as well.

Based on the description elsewhere in the comments, they don't sound very similar. ProtonPlus is just a download tool that lets you see and download or delete updates for all the various versions of Proton, so you don't have to visit a bunch of different Githubs. It doesn't let you see or change which version each game is using, which it sounds like ProtonUp does.