[Kiteboarding] Most aerobatics and tricks (tail grab, barrel roll etc.) can be executed without the airfoil's position in the air having to change. Therefore, executing "aerobatics" is only marginally different from executing them on shore suspended by the harness from some fixed point. Beginners with a lot of caution may start attempting some basic tricks after the first few weeks or even days. [Windsurfing] With most aerobatics the airfoil's position in the air tends to change dramatically, very much like it does in an airplane. Each figure has its own ideal airfoil movement. With some aerobatics like the barrel roll, the rider needs to jump sufficiently high to allow the full length of the mast to rotate forward underneath. Often the risks to the rider of having fast moving and relatively heavy (board + mast + sail) gear so close by are substantial. None of this is similar to any action onshore, and therefore the learning curve is very shallow. As aerobatics are considerably more complicated than jumping, they are the done by the most experienced of riders, commanding huge respect within the sail boarding community. [0] 
Aerobatics