Debian uses systemd as its default init system
Devuan was created specifically to avoid systemd, offering alternatives like SysV init, OpenRC, and runit
I do not know what an init system is. I don’t know what systemd is. I do not know what Devuan is. I do not know what SysV init is. I do not know what OpenRC is. I do not know what runit is.
I vaguely understand what debian is. Although I would be the wrong person it explain it. I know it’s the type of linux that ubuntu is. And I know it seems like every disto I look at says it’s based on ubuntu, and therefore is debian since ubuntu is based on debian.
What I don’t understand is if everyone hates ubuntu, but ubuntu is based on debian, but nobody hates debian, why is everything based on ubuntu and not debian?
How do I know if I want the debian version of a distro, or the devuan version? What are they even talking about?
The init system is the first thing that runs on boot and kind of allows other stuff to run. It’s not really something the average user needs to worry about.
Systemd is probably the most common init on Linux distros these days. Some people don’t like it. One reason is because it does a lot of things in addition to what traditional init systems do and that goes against the Unix philosophy (do one thing and do it well).
SysV, OpenRC, and runit are all more traditional init systems. I don’t really have experience with them.
Devuan is basically just Debian without systemd. It’s name is derived from Debian and VUA (Veteran Unix Admins, if I remember correctly).
Debian is a Linux distribution, meaning that it’s a complete operating system based around the Linux kernel.
Ubuntu is another distribution and is derived from Debian. Ubuntu makes a lot of changes from Debian. It would be better to think of their relationship as parent and child rather than a superhero’s alter ego.
Ubuntu is run by a company called Canonical. Over the years Canonical has made a number of controversial decisions (which I won’t get in to) and that’s why a lot of people don’t like Ubuntu.
Debian, on the other hand is community run. Additionally, they tend to not make radical changes since their focus is on providing a stable operating system.
As for why there are more Ubuntu based distros than Debian, I’m not certain. My guess is because Ubuntu is (or was?) more user friendly out of the box and it was a lot of people’s first distro for many years.
For your last question, I’d just go with the Debian version. As a beginner it would probably be easier to find help with that version. The Devuan version is aimed at more experienced users and old school sysadmins.