Based on your equitation and your horses movement, and your turn-out, not timed either, some classes judge on confirmation as well, and the quality of your round (example: when a course is posted, it will tell you how many strides in each combination) . Excellent manners, comfortable gaits are a big for Hunters.
You are timed. you can get defaults if you have rails down, refusals, falls. Not based on your turn-out, for example: Higher level Hunters you need to wear tall boots, Jumpers you can wear half chaps.
Whomever has the fasted times after their faults goes into a "Jump Off", basically it's a harder course then what was in the class; sharper turns, roll-backs, etc. Your horse is aloud to wear jumping boots, martingale, draw reins, etc, where as Hunters you are not aloud
This is my attire in the Hunters:
And the Jumpers(I still wear tall boots, I like matching my colors for fun, but I am "concervant" you would say and like to look classy lol, a lot of jumpers have bright colors) :