The biggest difference, I think, is rolling releases. For gaming, I don't really understand why anyone would prefer slower update cycles since there are frequent updates that fix compatibility or increase performance.
CachyOS is set up to install everything needed for gaming from the main Hello app. Once the Winboat and Gaming one-click installs are run, it just works. I got an itch.io .exe game running by double clicking the .exe. For Steam, I just needed to choose a default Proton compatibility package to use in the app and after that it's been seamless.
CachyOS is apparently "optimized" for gaming performance—I don't pretend to know what that means or how much of an impact it has. I don't really care about eking out a tiny bit more performance, tbh. But I'm super impressed with how well everything just works and (as a bit of a power user) how completely customizable things are, so I can install just about anything I need easily.