"i really don't understand the difference for example Gnome , KDE, LXDE, etc i see some of the same distros have multiple versions with those things there..."
when you create a distro you can choose to put a version of gnome or kde, lxde between many others, or all
also you can choose to add certain tools or not in each desktop
you can choose to have a certain kernel or a set of kernels to choose from in your distro
each distro points to a specific direction a specific goal, offer the latest, the most specific, the most options in software, the bleeding edge on kernel and apps versions while choosing a specific desktop or a set of desktops that goes according to their goals
pclinux in particular chooses kde4 as the main de because it is more friendly for us, users that come from windows and like something that resembles it, also we use a specific stable version of kde, maybe there is a newer one but we use the most stable available because one of the goals of this distro is offer a user friendly distro that is very stable and that can be reached by choosing a stable version of the desktop environment we use
we also have gnome but version 2, version 3 is not being much accepted really and for the moment version 2 is working for most users here, afik
other desktop environments offer different options in design, response time, system requirements and ways to do and handle actions
each desktop environment like gnome, kde, lxde, e17, openbox(to mention some) tries to do things their way, covering as much aspects of a desktop as possible while trying to reach certain expectations
not all the desktops offer the same tools but some tools exist on every desktop like a app to take screenshots, tools to record audio, to configure details of the desktop and similar stuff
each desktop is made by a different team, a different group of persons trying to reach a goal, each team puts their goals
when you run a desktop and you find that it is fast, looks nice, works the way you usually work and doesn't uses much resources(important in machines with limited resources) you can consider on choosing it as your desktop environment
a example of why a desktop exist is gnome, it is inspired in osx desktop, it also has alot less options to configure when compared to kde4(the king in customization i think) to keep it as simple as possible while remaining very functional and good loking
lxde is a mix of performance, low resources consumption and the style of the old kde3 desktop with a nice modern gui
e17 aims to be the prettiest desktop around while being light in resources, you can visit each desktop environment websites and read more about their objectives and reasons to be the way they arehttp://www.kde.org/http://www.gnome.org/http://www.enlightenment.org/
more links herehttp://en.wikipedia.org/wiki/Desktop_environment
"Does each one do something better than the others??"
no, there is not a better one, it depends on you, how you use it and on what hardware you will use with it
some desktops are better for some activities but others are better on others, in general you can do the same in almost all the desktops
"i had no\o clue he was "famous""
i didn't had a clue either, on this forum, there is not much famous users, only a couple losers with big post counts, try to ignore them