Alisa said:
Linux Provides two GUIs one is KDE and Other is Gnome. But Unix is command Based Operating System.
Unix is an operating system that is very popular in universities and big enterprises etc.
Linux is a kernel generally distributed with a GNU userland utilities and shell. Though Gnome is part of the GNU project (iirc) while KDE is not.
X11 is a MIT project.
There are more than two desktops though you mentioned the ones with the most bloat which have been part of the "Year of the Linux Desktop" meme since the mid/late 90's.
I for one have never seen a desktop run at the kernel level which may have caused the confusion in the first place. Though the GNU/Linux combination has been able to compile and run X11 with TWM since 1994 when the kernel release number hit 1.0 (back then hitting a whole number meant maturity)
BSD UNIX is a complete OS. In the 70's Bill Joy started the project at Berkeley University. Back then it was a patchset built on top of Bell Lab's UNIX. UNIX was inspired by MULTICS. The Multics Project was part of project MAC with participation from Bell, Honeywell and MIT at MIT. Multics was a project funded by DARPA in effort to see if there was a future profession to be known as computer science (i.e. combine mathematicians and scientists to become what then was a new activity called programmer). MIT had CTSS before MULTICS.
There was READ THIS which everyone receives when signing up for this forum. The link may have been "FreeBSD...What is it?"
It may have suggested that the modern networking stack and internet protocols where implemented on BSD (also by Joy). This would open up communications which later lead to the world wide web.
The world wide web has a common used start page called a search engine. This can be used to find out interesting facts on the differences between one manufacturer over another. For example the other day I wanted to know if what the difference between a rear wheel drive dodge challenger with a hemi was to say boeing 747 engine. Strangely I couldn't find a good compare and contrast. I read the challenger may have better gas mileage but no actual benchmark or fact.
Though I just did a search for "Difference between Linux and Unix?" and found something called POSIX. I think it stands for "Piece Of Searching Internet eXtended".
=)