What is the relationship between Ubuntu, Kubuntu and kernel?
And do different distributions of Linux, such as Red Hat, openSUSE, use the same kernel?
When you say Linux that actually means the Kernel, I think that's what you mean by "kenral"
so this kernel is being developed and a bunch of people or enterprises take it and build something upon it for example :
A community of people took the Linux kernel add some software and then created an Operating System called Debian. Then a company took that Debian and created something called Ubuntu.
Then.... you get the idea so this is why there are a lot of Operating systems based on Linux, but since they all have this Linux software in common they are called "Linux Distributions".The Kernel is just a piece software, make the bridge between Hardware and Software.
Ubuntu and Kubuntu are both "buntu" because they are based no just on the Linux Kernel but on Ubuntu either (Ubuntu it's based on Ubuntu... you get it) the difference is that Kubuntu uses a different environment called KDE, from there the 'K', Ubuntu uses gnome with unity on top of it.
There are a lot of Linux distros out there but there is a way they differ them.One way to distinguish them is by the type of packages they use some use ".rpm " some use ".deb"... or by dependency resolver, the software that makes sure that when you install a program you have all the little software needed for that greater software to work.
For example Ubuntu uses (.deb) and apt-get , Opensuse uses (.rpm) and zypper
