You have to let the ball bounce in the service box before returning the serve.
Returning a 120+ mph serve is by far harder because there is a bigger area where they can serve were as baseball players barley have to move their feet because of a strike zone. Also there is a smaller distance between the ball and raquet. Tennis players have to be on their toes constantly and needs a lot of strength to return serves.
Simply returning a serve is usually a defensive move: the initiative is left with the server. However, if you have an effective team, more than one hit enables you to attack rather than simply returning the serve.
You can hit an underhand serve in tennis; however, the overhand serve is more effective because it is more powerful. That is why you don't see the underhand serve used much.
Badly.
a serve
A tennis ball!
If you step on the white line in front of you while serving, it is illegal, its called faulting
Boxing, Football (soccer), rugby (returning 2016), Table Tennis, and Tennis.
It depends on how hard you want to hit the ball
a tennis ball
A tennis ball.