The Studio kit is meant for the person who sets it up in one place and never (or rarely) moves it. Main because of the type of clamps it uses. You need the drum key to adjust all the clamps.
I can't believe I get to do this to the man, the myth, the legend... but Phil is mistaken. The studio kit has butterfly bolts (or whatever you call 'em) for the clamps. Drum key is not needed.
A big difference in cost is material used in the rack. The Pro is Chrome'd, while the Studio is Powder Coated Aluminum.
Also, price wise, Surge Cymbals are 2-3x more expensive than plastic/rubber cyms.
I like the studio not only because it comes with an extra pad, and extra cymbal, but because the price point is $999.
Not trying to sell you one over the other, just giving you my opinion/reasoning on my purchase.