Four phases:
- Dressage
- Ease of Handling (obstacles at a comfortable speed)
- Speed Trial (simpler obstacles as fast as you are willing to go)
- Cattle handling in teams (not often available)
Each of the phases can be performed separately or skipped (for example, there is no requirement to do the speed trial).
Beginner is walk/trot only
Intermediate and advanced introduces canter
Here is a video that gives a nice overview