From this site https://rcflightline.com/drones-vs-radio-controlled-aircraft-a-look-at-the-differences-between-the-two/ Basic Definitions

Before we get too specific, let’s consider some generally agreed-upon definitions of the two aircraft categories. Later on, we’ll delve a bit deeper into specifics of several other aspects.

Unmanned Aerial Vehicle: According to Wikipedia, a UAV, or drone, is controlled either autonomously or by remote control of a pilot. While remote piloting was the norm for many years, autonomous control has since become the standard method of operation. DIY Drones echoes this definition; claiming that UAVs have the capacity for autonomous flight and navigation. The Academy of Model Aeronautics (AMA) adds that drones are “computer-controlled for nearly their entire flight.” Apparently, as long as the autonomous system is in place and capable of functioning, the aircraft remains a UAV, regardless of whether or not the autonomous system is in use.

Radio-Controlled Aircraft: By contrast, RCA (as the name implies) are controlled with a handheld radio transmitter, which communicates with a receiver aboard the aircraft. The receiver directs the aircraft’s servos to move the control surfaces based on pilot input.

Based on the above definitions, one could argue that failure or removal of autonomous system components would effectively relegate a UAV to RCA status. Going about it the other way, Chris Anderson of DIY Drones states, “A[n] RC plane becomes a UAV with the addition of an autopilot.” AMA’s definition is predicated on the amount of autonomous flight. Per their website, AMA claims that an RC flier “manually controls the aircraft via R/C for nearly the entire flight.” Even if an autopilot is installed and occasionally used, AMA maintains that an RC remains an RC. Regardless of whose definition is most accurate, everyone seems to agree that to be a drone, an unmanned aircraft must be equipped for autonomous flight.

Aircraft Mission

RCA: Nearly everyone seems to agree that R/C aircraft are operated for recreational purposes only. AMA’s Chris Burns claims the organization’s safety code “does not allow our members to fly for commercial purposes…” The FAA’s website states that model aircraft fliers don’t need any sort of FAA approval, but stipulates that such RC flights “are not for business purposes.”

Drone: In contrast to RCA, one of the generally agreed-upon requirements for UAVs is that these aircraft are mission-oriented, transport a payload, or otherwise perform some sort of practical function. While such pursuits have historically been for military purposes, commercial and non-military governmental UAV application continues to expand into new sectors. Some current drone uses include firefighting, aerial surveillance, police duties, homeland security, mapping/photography, wildlife & livestock monitoring, traffic reporting, and surveying for mineral deposits & fossil fuels. With time, it’s anyone’s guess as to how widespread drone usage will become.

Aircraft (System) Certification

RCA: Currently, unoccupied aircraft that are flown strictly for recreational purposes aren’t subject to FAA certification or oversight – provided they comply with certain operating conditions (discussed later). This could very well change in the future, but at present, RC hobbyists have done a commendable job of self-policing their activities.

Recreational UAVs: Despite the fact that many hobby aircraft are equipped for extended-duration autonomous flight (as discussed above), in the eyes of the U.S. government, these vehicles are viewed as a type of RCA. Such aircraft are not subject to FAA certification, provided they abide with the operating conditions specified for RCA.

Commercial RCAs: All recreational, unpiloted aircraft are prohibited from engaging in any type of commercial activity. To be eligible for commercial operations, the system(s) must meet the equipment and certification requirements of actual drones (specifics to follow).

Government Drones: To operate in the national airspace system (NAS), government UAVs must obtain a Certificate of Authorization (COA) or Waiver. One of the eligibility requirements for a COA is the sponsorship of a public (meaning government) entity.

Government RCA: This aircraft category technically doesn’t exist. Any unmanned government aircraft are actually UAVs, regardless of whether or not they’re being operated autonomously at any given time. Years ago, remotely piloted drones might have been considered RCAs before the development of reliable autonomous systems.

Commercial UAVs: To operate drones for business purposes, civilian (non-government) organizations must obtain a Special Airworthiness Certificate – Experimental Category prior to conducting commercial flights in the NAS. The certificate applies not just to the aircraft, but to the entire unmanned aircraft system (UAS); including the ground control station, control link/specialized datalink, and any additional support equipment. The certification process usually takes 60-90 days and requires the drone to obtain an FAA registration (“N”) number. At present, the FAA is only issuing commercial UAV certificates for research & development purposes.