how many distances are there in table tennis?

hey guys.....
i was looking at the videos they posted of chinese training.
http://www.youtube.com/user/Wingline2
how many different distances exist?
i can see a close distance, near to table....
a slightly bigger distance, which is the distance ma long is in, in the chen qi  video.
and then there's the loop vs loop distance.
i don't know when to use any of these distances, nobody ever taught me anything about distances, here when we train there's no such concept as distance, just hitting the ball.
for example:
here ma long is pretty far from the table when making a top spin...
http://www.youtube.com/watch?v=sJeZ8JIX9Z4&feature=channel_page

and here he's much closer
http://www.youtube.com/watch?v=MrY9ICIxfYY&feature=channel_page

enlighten meeeeeeeeeeeeeeeeeeee