My CZ has two crossbolts that look like two Phillip's head screws screwed together. I've noticed other CZ rifle's crossbolts have what looks like a round disk with two holes in it. Can someone please explain to me the differences between the crossbolts. Are there any pros/cons between the different variations? Thanks.

They are just variations of the same. The type of bolt/screw head matters little except for appearance. The nicest I've seen are actually recessed, with a wooden plug sanded flush with the sides of the stock so the screw heads themselves don't actually show. I installed a number of crossbolts in my CZ in .458 Win. in a blind fashion, so they don't show at all.