How to (install and) update AppImage?

The Appimage is quite fast. It is already in version 1.9.7, the PPA and the FlatPak have not yet been updated.

Is there any difference between the stable version and nightly AppImage?

I want to keep a stable version of AppImage, but it has no update package. So, what is the correct way to install and update the appimage?

PPA should be updated (and snap) already, but to update the AppImage, just download the new version and, if you’re using the portable home directory, just overwrite the old one with the new. If you’re not using the portable home directory and it’s writing everything to ~/.config/retroarch, just start using the new one and throw out the old one.

The stable and nightly builds are identical today, but as more commits are added to RetroArch, the nightly will move ahead of the stable build (which will not change until the next stable release).

Yes, I have updated that way in a Portable Directory, with the Update file. I wanted to be sure that the nocturnal version somehow affects the stable.

It still updates from the PPA, but it has more than 4 hours updated, O_o there is no hurry, it is just a curiosity.