American Roulette and European Roulette may look the same upon first glance, but a closer examination reveals key differences between the two games. You’ll be aware that the zero and double zero in American Roulette is generally bad news for the player. The exception is when you have placed a bet on the white ball landing there or took out a Five Number Bet (more of that later). All other bets on the table are forfeited.
In European Roulette, the numbers on the wheel are in a different order, and there is no 00 segment, only a single green zero. It’s a small distinction, but one, when you understand the nuances, that can make a significant difference to your win rate in the long term. (資料來源)