Skeet is essentially a closer-range game than Trap.
Trap and Skeet are both shot (25 shots/chances/targets per game) from the same 5 stations (1 central station if single Trap is the game), spaced around a half-circle, but the centrally-located trap (pigeon/clay bird thrower) is at various set distances ahead of the shooting line in Trap, all targets/birds moving "away" from the shooter.
Each of the Skeet traps (there are 2, 1-"low" house, 1-"high" house) are at one end or the other of the half-circle diameter, and throw their targets/birds generally towards one another ( a little away from the shooter) - resulting in either/both high and/or low left-crossing, right crossing, incoming, and/or out-going targets/birds, depending upon the shooter's position.
Both games have "Singles" (one target) and "Doubles" (two simultainious targets) competition.
IMO, "Trap" was instituted to simulate the driven/flushed bird shooting of weathy European landwoners; "Skeet" to simulate the close-range "rough" bird hunting/jump-shooting of commoners.