tig is a slower, much more precise process. and when done right, a beautiful looking weld. with tig welding you have the torch ( kind of like mig, but it does not shoot wire, it only has the current) in one hand and with your other hand, the filler rod. you push a foot pedal down to control the current, and dab the filler rod into the arc.
EDIT: watch this. http://www.youtube.com/watch?v=OfOqyqKR0IU&feature=related