The US Military has five official group of UAVs/drones.

(from ATP 3-01-81)

The standard hobby drone is a Group 1. Smaller military drones are groups 2 and 3. The ScanEagle is the best American example of a Group 2. The classic Iowa spotter Pioneer is a Group 3, so is the RQ-7 Shadow. Heavy attack drones like the Predator and Bayraktar TB2 are 4, while monsters like the Reaper and Global Hawk are 5.