Debian is what might be noted as a top level distribution. A distribution in Linux parlance is similar to a recipe. Let’s look at that so that the rest of this makes sense.
At the beginning of Linux since it was open and free it meant that you had to have some technical knowledge to make it work. To get it installed you would compile everything and build the OS. Everything was compiled. You configured everything.
This was quite a burden so groups of people started their own recipe of sorts to make it easier for other to use Linux. Instead of you compiling it they did all that work and assembled it like a puzzle and then distributed the end result. These ultimately were turned into ISO files. ISO files are images of say a CD ROM. ISO is the internation standards organization and they set a specification for CD ROMs. When the image was completed the ISO was written to a file and made available to the rest of the world. That’s a literal meaning. The rest of the world could download the ISO and burn it to a CD platter. Then you could boot with that and ultimately install Linux onto your hard drive.
So, there are different recipes. Debian is sort of one recipe. Arch is another. Gentoo is what Google built Google chromebooks on. There are a lot of them.
Debian was used as the basis for Ubuntu. The people at Canonical built Ubuntu and created an ISO and put it on the web for everyone to download and use to install it on their computer. From that other distributions were created. Kubuntu, Xubuntu, Lubuntu, all derived from Canonical’s Ubuntu. They were just different recipes. One recipe may have the KDE Plasma desktop environment. Another might have XFCE desktop environment.
The Arch distribution had a number of derivities. Manjaro is derived from Arch. Garuda is another. Again each one distinguishes itself from the others in some way. Some distributions have multiple ISOs that they release with specific desktop environments.
Red Hat created various distributions such as Fedora. Red Hat has Enterprise Linux or RHEL. From that distribution Centos was derived. Others also created distributions that were near identical to RHEL. Some had their own spin.
SUSE is another distribution that is similar to Red Hat but branched off from Red Hat years ago.
Some other distinguishing differences are that these distributions have what are called package managers. These package managers control the installation, update, and removal of the different programs that you install as well as updating the operating system files.
Most of the Ubuntu based distributions have APT as their package manager. This includes Kubuntu, Lubuntu, Xubuntu and maybe a hundred other derived distributions.
Arch uses pacman. It has similar functionality to APT. A distribution is created because a group of people thing that they can improve on the work of others. Pacman is the package manager for Arch that has as much functionality as APT and maybe more.
Red Hat and Fedora gives you the choice of several package managers that all use the same basic underlying programs to manage your software.
Distributions have code names for their releases. Ubuntu uses names of animals with a silly surname, such as Groovy Gorilla. Or Jammy Jellyfish. Debian uses names like Jesse, stretch, buster, bullseye. These names just indicate the release of the distribution.
There are different types of distributions. The most common is the LTS, which means long term support. It means the OS is updated but generally only to fix some nagging issues and security features. They want the distribution to remain unchanged for a long period enabling users to feel comfortable and stable. The next is a rolling release. This is where the OS is updated all the time. Every day you could have updates. With an LTS you can have updates every day but you won’t get major package updates due to new releases of them. For instance the install of LibreOffice. You’ll get the base stable version of LibreOffice as it was at the time the distribution was released. If a new version comes out you don’t necessarily get that update. A rolling release means you are going to get the bleeding edge — or the most recent releases — but the peril is that if the new release is buggy that will impact you.
Debian – jesse, stretch, buster, bullseye
Ubuntu – groovy gorilla, hirsute hippo, jammy jellyfish, impish indri
Red Hat – has their own system of naming releases
Fedora – has things like 34, then 35, then 36, etc For fedora 34, Fedora 35.
The schedules of releases for an LTS, say in the case of Ubuntu, those are released every 2 years. The non-LTS versions are released every 6 months.
You might be thinking about KDE Plasma, Gnome, or one of the other names you’ve heard. These are desktop environments. They have different looks and feel and thus are different paradigms. This is not part of the name for distributions. Groovy Gorilla is done by Canonical with their Ubuntu distribution. It is a code name for a release of the distribution. The next version that was released later is called Hirsute Hippo. The only way we know what desktop environment that is in this distribution is because we know what desktop environment that Canonical supports. They support Gnome. The Kubuntu distribution is a derivative of Ubuntu where they replaced the Gnome desktop with the KDE Plasma desktop environment.
You can go to their respective sites to determine which desktop environment that any given distribution supports.
Linux Mint supports numerous desktop environments. They typically have separate ISO files that you can download for a given desktop environment. If you want the Linux Mint Cinnamon desktop there’s an ISO for that. If you want the KDE Plasma desktop there’s a distro for that. There are several others that are just like this. Again, just go to the websites to determine which desktop environment any given distribution supports and if they also have alternatives.