The Cross rail uses 2 poles to create a jump when it’s lower in the middle. It is often used with beginners or for easier jumps/warm-ups.
A vertical jump normally uses either 1,2 or 3 poles stacked vertically. Often 3 poles are used in competitions but just 1 in training. These are the most standard jumps.
Oxers are set up with 2 jumps very close together, focusing on the jumping distance rather than being very high.
Triple bars are 3 jumps close together that increase in height forming an increasing angle. These jumps are more common in experienced competitions.
Very helpful, thanks!