I tried out Red Hat, Ubuntu, Kali Linux. While working on them I searched for the difference between the distributions of Linux. One thing I got was the difference in Package Management, (.rpm and .deb). But I don't think it's only the difference.
Secondly, while trying some commands on Kali Linux (like quotacheck), it's giving no results. So how can I know which distribution support which commands and also how to enable them?
Thirdly, I read that Kali OS is based on Debian. So what does based on really mean?
Best Answer
comparing distros
I'd start first with the comparison of Linux distributions on the wikipedia page titled: Comparison of Linux distributions. Distrowatch is another good resource for comparing Linux distros.
The site Digital Inspiration also has a good article titled: Which is the Best Linux Distribution for your Desktop? which has invaluable information in showing what each distro's primary target audiences are.
based on?
The "based on" term is exactly what the name says. Linux distros can be complicated to setup and maintain. So often times people want to take the guts of an existing distro and use it as a base for their own distro, changing only pieces that they really care about.
Debian, Ubuntu, and Linux Mint are good examples of this. The Debian distro is a pretty old and expansive distro. So it has lots of architectures and packages available.
So the Ubuntu distro takes Debian at its core and expands upon it, changing the desktop among other things. The Linux Mint project takes Ubuntu as its core and further expands upon Ubuntu, again changing the desktop, file explorer and such.
The true advantage to this is that each "child" distro is able to leverage from it's "parent" or "grandparent" distro.
packages?
Looking up packages across the distros is next to impossible in a systematic way, to my knowledge. This site has proven useful in looking to see what packages are available in most of the larger distros. The site is called pkgs.org.