Trap are generally going away target shot from certain distance away. Generally speaking american traps are played in a group of 5. Everybody gets a shot and rotates position on the line.
Skeet are shot from high house and low house. You move in a semi circle line and shoot each station. Skeet is a fairly repetitive game as each target is the same for the station.
SC has more variety of presentation from towers to rabbits. There are no set way plan a SC course and may will change it up through the season.
They are all good games, depending on your skill level, skeet and trap are easier to master and work on parts of your game due to you being able to know the presentation before the shot.