Roulette varies in different regions primarily through its rules, wheel layout, and the number of pockets. European Roulette features a single zero (0) and has 37 pockets (numbers 1 to 36 plus 0), resulting in a lower house edge compared to its American counterpart, which includes a double zero (00), bringing the total to 38 pockets. This difference increases the house edge in American Roulette.