To be honest, not a lot. You may be able to tell a very very minute difference when using different hoops when playing the snare by itself, however when playing with the other drums or in a band the difference will be pretty much unnoticeable to anyone except yourself, if even that. I wouldn't worry about it.
More pop or crack? Try changing out your heads and snare wires, they will have a MUCH bigger influence. For pop and crack I would recommend a controlled sound be remo, or an ST by evans. Not a big expert on snare wires, but puresound is the biggest manufacturer. Check out their site, I think they've got plenty of info on their products.
"Nowadays you could find a plumber, put him in a studio and make him sound good." ~John Robinson