Why are there so many different Proton versions? Proton 8, Proton 9, Experimental, GE-Proton
Why are there so many different Proton versions? Proton 8, Proton 9, Experimental, GE-Proton

www.gamingonlinux.com
Why are there so many different Proton versions? Proton 8, Proton 9, Experimental, GE-Proton

Different branches and different versions. Sometimes there are regressions between new versions. Sometimes the fixes are pushed in certain branches and not others. They are generally provided for stability and compatibilities sake. If you find a version that works for your particular game. You should be able to keep it around and run your game safe and stable unless something on the game gets updated. But outside that you should probably try to run with whatever the latest stable is.
Just to add to this a bit with some visual context, you can visit proton's github page and look at their releases to see the improvements valve has made to each version.
https://github.com/ValveSoftware/Proton/releases
This can help put what Eldritch said into practice.
If you are having issues playing a game you can visit https://www.protondb.com/ and search for your game. Here you will be able to find what versions of proton others are using. Look for people with similar setups and match the version of proton that works for them.
Thanks for this!
But what about Experimental? Is it just a beta of some other release?