According to the FAA, only the term UAS is proper although they recognize that there are small UAS AKA sUAS. The term UAV is officially dropped although still used by many, even in the FAA, old words die hard.
Everything from a rubber powered balsa airplane to a huge US military drone is a UAS.
Anyone claiming that model aircraft, flying toys, FPV and/or autonomous systems is somehow not UAS is wrong. They are all UAS
An analogy would be motor vehicles. Motorcycles, mopeds, motor scooters, minibikes, cars, trucks and buses are all motor vehicles. All are different and have different rules, regulations and restrictions.
That is how the FAA's coming UAS rules and regulations will be. The breakdown and separation of different types of UASs is readily apparent if you simply read the 70 odd pages of the FAA/ARC proposal document.
I thought I needed to mention that the USA Govt uses the term sUAS to describe UAS at or under 55 pounds.
sUAS <= 55 #
UAS 55 # >
Duanes right anything other than UAS is non sense, although RPAS RPA and nUAS and pUAS are also out there.
What people also need to keep in mind is that the S also includes your GCS and telemetry its not just the airframe and autopilot.
I can't remember how they did it but I know the CAA in the UK had an awakening and realised they would be banning paper aeroplanes if they were not careful so they worded their regs very well. I will maintain the UK has decent regs because there are real aviators sat behind the desk. At the Farnborough press release one of the ex CAA guys flew a Spitfire in and displayed it.
@Martin those rules you quote are for models, not UAS. CAP 722 is changing again in April but I don't believe there are any airframe requirement changes for sub 20kg airframes. We might move closer to CPL(U) though.
I cringe at the term "UAS". A "system" according to one dictionary is "an assemblage or combination of things or parts forming a complex or unitary whole". A UAV by definition is already a system. Referring to it as a "system" is redundant.
Even worse, the term "UAS" is too vague to be useful. A thunderstorm is a UAS, because it is unmanned, it is aerial, and it is a system, albeit one formed from different masses of air at different temperatures and humidity that interact with the Sun and the turning Earth. Same with a hurricane.
Even worse, "UAS" just doesn't roll off the tongue. :)
I prefer UAV and MAV.