​Firstly, I want to emphasize that beginners and amateurs can also use green, pink, and blue ping pong paddles. However, the official ITTF rulebook (International Table Tennis Federation) states that the professional players have to use paddles with two sides: black and red. This is the so-called "two-color rule". When you play a professional match, your opponent has the right to inspect your paddle, so that, during the game, the color of the side you're using can signalize what to expect. But other than the regulations, the black and the red side of the paddle are NOT the same. The red rubber is harder, less tacky, and faster. This means there'll be fewer opportunities for spins and trick shots, with a focus on the speed of the game. On the other hand, black rubber is softer and tackier, meaning that you can alter your shots on the ball a bit more, but you lose on the speed. Therefore, one is not better than the other - you just have to find your style for forehands and backhands, and then decide which side to use.