There is a couple of various different roulette games, most of them looks like the same and doesn´t various a lot. The main roulette variants is European roulette and American roulette. The main difference is that on American roulette there is a double zero, only increasing the casinos chance of winning. European roulette or French roulette is the most popular version that many are used to.
When you enter a casino site you will also notice they have many different equal types of roulette tables, mainly the difference is usually the bet sizes for the table, for example one table has a minimum limit on €1 and another has €100 minimum, all depending on what type of player you are.