I think Drone / UAV can be interchanged.. I think the big differentiator should be the autonomous flying capabilities. Otherwise, I think of the stuff that individuals fly around as RC Aircraft even with a camera onboard which provides the person flying it with the ability to see from the aircraft in real time. Drones, as the term is popularly used these days, tend to refer to a military use UAV which packs weapons or sensors used for military reconnaissance.
Unmanned Areal Vehicle: A powered, aerial vehicle that does not carry a human operator, uses aerodynamic forces to provide vehicle lift, can fly autonomously or be piloted remotely, can be expendable or recoverable, and can carry a lethal or nonlethal payload. Ballistic or semiballistic vehicles, cruise missiles, and artillery projectiles are not considered unmanned aerial vehicles. Also called UAV.