It will surprise nobody that real fighting or full-contact competition differs from movie fighting. What is perhaps less obvious is that the incentives for the actions are completely opposite. The actions themselves are not completely opposite, because movie fighting is supposed to look somewhat like a real fight, which constrains the difference between them.
An obvious incentive difference is the desire to hurt an opponent in a real fight vs not hurt a fellow actor. A more subtle distinction is that in a real fight or competition, nobody wants the opponent to see a punch or kick coming. In a movie, the flashier and more visible the attack and defense, the better. So in a real fight or competition, the movements are quick, preferably without wind-up by other parts of the body, mostly in a direct line from one body to the other (although some curved punches and kicks are used). The movements may be masked by feints, but these are subtle, like eyes flicking right while punching with the left. In a movie, the kicks especially move in long visible arcs, with the body turning 360 degrees in some cases, and not too fast. Every move is designed to be seen by the audience, which implies seen by the opponent.
In a movie fight, the techniques should not repeat, otherwise the audience gets bored. In a real fight, the only reason not to use one’s best move exclusively is the need to surprise the opponent. Only a few of the most effective techniques are used. Another reason for this is that real fights end quickly (not counting the posturing and shouting), so there is not much time to showcase a variety of punches and kicks. A wider range of moves is used in competitions, but still not close to the range in movie fights.