Aircraft encompass all airborne flying machines governed by some sort of government regulations and if they are operated by pilots these personnel need to be licensed. However, the term unmanned aerial vehicle refers to a machine that can be used even by a layman and requires no regulated training or license of any sort.
Since the FAA is chartered to regulate aircraft, it coined the term remotely operated aircraft or ROA that defined all aerial vehicles remotely controlled by a user that didn’t need to be a certified pilot to fly these machines. The modern aerial vehicles are successors of those machines that were developed in the 1970s by Israel. These flying machines were meant for battlefield data collection and were responsible for sending back real-time data for analysis.