Backspin

Backspin: The easy-to-learn backspin strokes adds subtle lift to the first part of the ball-curve, lets the ball drop more suddenly, makes the ball bounce more upright and most significantly: makes the ball dive downwards when the opponent uses a common rubber (pimples inwards) on his racket. (The opponent is forced to seriously compensate for the backspin) Due to the initial lift of the backspin-curve, there’s a limit on how much speed one can hit the ball without overflying the opponents half. Backspin also makes it harder for the opponent to hit the ball with lots of speed. In table-tennis backspin is regarded as a defensive alternative, due to: the limitation on ballspeed, the simplicity of producing the strokes and the daring of the opponent. (It is possible to smash with backspin offensively, but only on easy high balls, close to the net)
4 phases in a topspin curve

Topspin: The hard-to-learn topspin strokes has a minor influence on the first part of the ball-curve, but the Magnus effect clearly forces the ball back down as it approaches the opposing side. On the bounce the topspin will accelerate the ball a little more. Again the most significant change appears when the opponent hits the ball (with a common pimples inwards rubber on his racket). Due to the topspin the ball jumps upwards and the opponent is forced to seriously compensate for the topspin. There’s virtually no limit on how much speed a topspin-ball can be given (besides your own timing and strength) and a speedy topspin stroke gives the opponent very little time to respond. In tabletennis topspin is regarded as a offensive alternative, due to: the virtual limitless ballspeeds, the highly required skills for producing the strokes and the enhanced tactical pressure on the opponent. (It is possible to play defensive topspin-lobs from far behind the table, but only world class players use this type of gallery play successfully)