Conformation, Style, and Breed are the big factors. Hunters typically have sloping shoulders to take big strides, are collected, have a round square jump,and are usually bays, grays, chesnut, or black. A perfect "hunter" horse would stay at a consistant pace throughout the entire course nailing every distance. The piccture above resembles a good hunter even though the riders leg has slipped back. A jumper horse can have big stides too but it isn't judged on"pretty" conformation like a hunter. They are faster paced and have a higher head carriage. Jumper courses have more rollbacks and combinations opposed to lines. They jumps are more colorful in jumper courses than hunters as well.