Many Linux distributions carry a distinction between the operating system and the desktop environment.
An operating system is the software that manages resources, and provides common services for applications to run. It schedules tasks for efficient use of the processor, storage, and network time. It also acts as the intermediary between hardware and applications. Crucially, it provides only a command-line interface and no graphical user interface.
A desktop environment is software that runs on top of the operating system and provides a graphical user interface. Desktop environments often carry their own sets of settings, keyboard shortcuts, and (importantly) default apps. Since desktop environments have a massive influence on the user experience, it can often make more sense to recommend desktop environments instead of distributions (operating systems) to new linux users.
While desktop environments massively enrich a user's experience of an operating system, the developers of a desktop environment sometimes create an operating system of their own. The reasons could be any or many of the following:
- The developers of the desktop environment may feel that none of the popular operating systems show off the strengths of the desktop environment very well
- The developers of the desktop environment may wish to provide a way for application developers to test the look-and-feel of their apps on the latest version of the desktop environment
- They developers of the desktop environment may wish to showcase their new features, especially to enthusiasts and reviewers, without waiting for an operating system to get an update.
KDE Linux and GNOME OS are two such "showcase" operating systems.
KDE, creators of KDE Plasma, the most popular desktop environment among more hardcore linux distributions like Arch, have announced KDE Linux as an experimental operating system with the goal of eventually becoming "the best choice for home use, enterprise workstations, public institutions, and more". In other words, they want it to become a major operating system. It has an immutable base, which means that once it is installed, the operating system cannot be broken (or "borked") by user error or remote attacks. Updates can also be easily rolled back on immutable operating systems.
It is based on Arch Linux and intends to keep installed applications separate from the operating system for security reasons in addition to reliability.
There are also multiple editions planned (because of course) for testing (daily updates, made for devs and testers), enthusiast (made for enthusiasts and power users), and stable (delayed updates prioritising stability for everyday users) usecases.
Since it is a newly developed operating system, they get to use all the buzzy new technologies in the Linux world. Immutable systems, I have already mentioned. The flatpak app format, Wayland image compositor, and systemd services are some of them.
GNOME, a desktop environment made popular by Ubuntu, created GNOME OS for experimental and development reasons. It is heavily container-based, with Flathub as the default app store. It also contains a bunch of additional developer tools for (surprise, surprise) developers to work with.
This comes one year after Germany's Sovereign Tech Fund invested a million euros into GNOME to improve various aspects of the desktop environment.
They intend to take an "opinionated" approach, reducing the feeling of choice paralysis for inexperienced users. This is in stark contrast to KDE Plasma, which focuses heavily on user choice.
GNOME OS is also an immutable distribution for reliability. With each OS copy being identical, troubleshooting is easier. There is, again, a focus on modernity to push progress.