The point is that at an online casino, you can find two types of roulette. A virtual and live one. A virtual game means playing using programmed software, where a PC (artificial algorithm) is your competitor, and the outcome of the game is determined by a random number generator. It means that you play a programmed game. When dealing with live roulette, here, you have real competitors (players from any part of the world) and a real dealer, whom you can see on the screen. Thus, it seems like playing a land-based casino via a webcam.