RTF (ready to fly) kits contain a built drone including all necessary equipment such as radio or charger. So just unpack and you're ready to fly. BNF (bind and fly) is a ready built drone that you just need to pair with a radio. PNF (plug and fly) is a built drone without RC receiver. You choose the one according to your radio. Finally, ARF (almost ready to fly) is a drone kit for build that contains the necessary components.