So SteamOS is what’s known as an immutable file system, which is where the system files can’t be modified by the user. This makes the system very hard to break for end users, provides easy system repair options, and is generally nice for a consumer device.

However immutable systems are relatively new, and historically most programs are installed to parts of the drive that are now “immutable”. This is a problem for installing software.

A recently popular software distribution system is called flatpak, and one of the nice things about it is that it installs software to the user section of the drive, allowing it to work for providing software in immutable systems. This is what the Steam Deck uses, available through the discover store. However flatpaks aren’t perfect, they lack some programs available from the traditional sources, and they often have trouble letting programs interact with each other. An easy example of this is a program like a password manager may need to integrate with your web browser to fill in passwords, but the flatpak versions of the browser and password manager can’t actually talk to each other and won’t work together.

Bazzite also uses an immutable OS, but it allows you to install select programs to the normally locked down system partition. This isn’t meant to be the main way to install software, but is a good fallback option for something that isn’t available or doesn’t work when installed through flatpak.

Bazzite also offers alternative desktop environments like Gnome, which has a more touch friendly user interface. Alternative desktops are not currently available for SteamOS in any reasonable way.