Hunters:
Normally a straight forward not to complicating course. Jumps normally include verticals and oxers. Roll tops, brush boxes, and flowers are normally under the fences. The fences are usually conservative colors (white, brown, black). In lower level shows there are normally 2 outside lines equal in stride, a single diagonal and a double diagonal that is either - or + a stride fot the outside line.
Equitation classes
Equitation classes are part of the "hunter circuit." Equitation is based on the riders skill of monuvering (sp) the horse around the course while keeping nice appearence. Equitation classes are basically the half way line between hunters and jumpers. The jumps are the same as the hunter classes but the course is different. Normally there will be 2 roll backs and places where you could take a short or long route. Normally there is a line where you can push your horse and cut a stride out or hold your horse.
Jumpers
Jumpers are more complicated which is why most people start in the hunter ring and work their way up to the jumper ring. The jumper ring normally consists of brighter fences, swedish oxers, triple bars, triple lines, in and outs, bent lines, etc. The jumps are an array of colors shapes and sizes (including skinnies). The normal jumper course consists of a first round and a jump off. The first round is all about staying under the time allowed and keeping the rails up, no need for speed or tight turns. The jump off is where tight turns and use of speed comes it (speed wont win a class its turning... but there is already a thread on that). There are also optimum time classes where you get as close to a certain time like 51 sec..There are also speed classes where you try to get the fastest time. And lastly there are power and speed classes where normally the first 8-9fences are like a normal course but then without stopping you go through another set of timers and it turns into a jump off all at once.
I hope this helps and if you have any more questions just ask