Upon reading various articles on Linux, I am confused on the difference between:

* X11
* Xfree86
* Desktops like Gnome

When I read about them, they all sound like the same thing. Can some one clarify it for me please?

* x11 and xfree86 (the free version of X-windows)
are methods of displaying windows/programs on a computer (whether remote or not)

* window managers
are programs that control how the windows look and act. it works on top of the X-windows system. they are things like XFCE or IceWM or Fluxbox, etc

* desktop environments
are many programs (a suite) that include programs like window managers, a program to display the 'start menu' / 'taskbar', and progams to display/control the actual desktop... all rolled into one. most popular are gnome and kde (K desktop environment).

thats just outta my head.. heres a link (i havent read it, hopefully its good!) that looks like (from the headings) it might have good/more detailed information about it! click me

DE's have applications like games, office, multimedia, and utilities in them, as well as what nadroj said. Xfce is actually a DE.
Some form of a start menu and taskbar is in most WM's. For IceWM, it is where you would expect them. Fluxbox and Window Maker use right-click to bring up a menu.
Xorg, XF86 and X11 handles the getting a videocard to do what it wants, and the ability to execute graphical applications over the network.