Best thing for you to do is browse Linux websites. Best one for documentation would be
http://www.linuxdoc.org
Other sites would be
http://www.linux.com ,
http://www.linux.org , and possibly
http://www.themes.org if you want to know differences in GUI interfaces.
Basically Linux is free under the GPL, its more stable than Windows platforms in general cause it is based off of Unix but is not Unix. You can do whatever you want to in Linux, compared to other closed source platforms. This can go on and on.....its best for you to search al you can on Linux to find out more.