First, all the low red numbers and black high numbers are on one side of the zero, and the high red numbers and low black numbers are on the other side. On the European wheel there are two other interesting symmetries.

But again there are a number of violations of this rule on both wheels. Both wheels also try to distribute odd and even numbers as evenly as possible. It is for this reason that the American wheel is considered not as balanced as the European wheel. On the American wheel, there are many examples where this rule is violated. On a European wheel, this is only violated where the 5 sits next to the 10 (both low numbers). The wheels are also structured so that the low numbers (1-18) and the high numbers (19-36) should alternate as much as possible.

On both wheels, the red and black numbers alternate around the wheel, although if you removed the zeroes, the American wheel would have consecutive reds and blacks. The numbers are arranged in a different order on each wheel but there are some similarities in the patterns. On an American wheel you can expect to lose 5.26% (if you are interested in the mathematics of roulette, the video at the end will show you how these odds are calculated). On a European wheel you would expect to lose, in the long run, 2.7% of any money you bet with. This is important as it doubles the advantage for the casino. Notice that the American wheel has two zeroes.

Pictures of roulette wheel layout