#2
its the pickups (and I think the wood).

The pickups in the vintage mahogany les paul are burstbuckers, I forget the name of the pickups in the studio is it p90's?

Anyways, the sound of the vintage mahogany is as you guessed, more vintage. Both sound nice, I've heard them played in unison and they both sound great.
#3
The Standard has a carved maple top and the Vintage mahogany has a mahogany top. Both have burstbucker pickups. The mahogany does not have the nitro finish on it. The Studio does but it does not have the binding that the Standard does. You can find all the info by checking them out on Guitar Center's website.
By the way, The Standard kicks ASS!