An endurance bridle has to be as comfortable as possible (because the horse will wear it for a very long time compared to other disciplines), it also has to be light but strong and flexible. The specificity is that it combines a bridle and a halter that can be apart to gain time during the veterinary controls. There is also a specific size created: "Arab" because there are a lot of purebred Arab in these competitions (they have a thinner head than other horses). They also are very colorful.
In comparison, a regular bridle is mostly in leather and different for every discipline (double bridle for dressage for example). It is more simple in the colors than endurance ones (black or brown).