There are two major kinds or types of roulette. These two kinds are American and European. American adds an extra number to the table and wheel as the "00," while European only has the single 0. This change was actually made by those that ran the casinos that played the game of roulette because with only one zero the house's chance was 2.7% and with two zeros the house's chance was 5.4%. The two types of roulette also differ by the way, or actually in what, chips are played. In Europe there are multiple denominations of chips being thrown across the table, such as poker, while American asks only for one amount of chips to be used by all roulette players. This makes the dealer or croupier have a much easier job in America because the chips are all the same.
European roulette also uses a bigger table than the typical American table. This is just for looks and really doesn't affect the game much at all. The third type of roulette is English roulette. It is a combination of the two games. It uses the English language on the board but only has one zero. It is funny that this is the only board that is allowed to be used in the country of England - they are very particular about their gambling.