European Roulette vs. American Roulette
Roulette is played in two versions, American and European. There are several differences between the two. We describe them here. Roulette came from France and both of its variations are French in origin.
Zero and Double Zero
This is the most obvious difference between the two wheels. The two zeros in American roulette almost doubles the house edge from 2.7% (for European) to 5.26%. The zero pockets are traditionally colored green to distinguish it from the red and black slots.
En Prison
This special rule is found only in European roulette. In a 1:1 bet (red/black, high/low, odd/even), if the ball rolls on zero, you do not lose your bet immediately. Instead the wheel is spun again and if the next spin is again a losing spin, you lose. But if the spin wins, it's a push and you get your money back. This reduces the house edge to a mere 1.35%, one of the best odds ever in a casino.
Sometimes an American roulette game has a rule similar to the "en prison." This is called "surrender." On a 1:1 bet, if the ball hits zero or double-zero, you lose only half your wager. You can take back the other half or you can keep it as a bet in case the next spin wins, in which case it is a push.
Call Betting
The numbers on a roulette wheel are arranged in such a way as to give no advantage to any bet. Yet the numbers in American and European wheels are sequenced differently. It doesn't change anything about the odds, but it does form the basis for "call bets" as they are known in European games. These bets cover a group of numbers on the wheel (not the board), e.g. all numbers between 22 and 25. Call bets are recited to the dealer instead of being made on the roulette betting board.
Betting Chips
In American roulette, special betting chips are used to indicate your bets. These are not the usual play money chips used in casinos. If you were to pocket betting chips, they would be useless elsewhere in the casino. But the standard playing chips are used in European roulette.
A roulette table usually has about half a dozen players. To avoid confusion, each player has uniquely colored betting chips to distinguish them from other players' chips. The worth of each chip depends on what a player bought in for, so one chip for you may be worth $10 and $40 to the next player. There is no way to tell unless you see them buy into the table.