How to tell the difference between a UFO and a drone
A UFO can change it's appearance as you watch it. The lights seem to have a shimmering quality to them that can change in intensity, color, size and shape. A UFO can disappear and re-appear while your eyes are on it. A UFO can move in a very erratic way, it can dart around the sky, it can go up, then down, left and right. A UFO can go very fast then stop to hover in one place. UfOs can come down close to the ground then suddenly dart up in the sky and out of sight. The more common shapes for a UFO is a flying saucer shape or triangle shape.
. Go online and look at all the different pictures of Government drones and of UFOs. Learn the shapes and sizes of the drones. Watch videos of drones flying at night and then watch videos of UFOs in the night sky. Teach yourself how to differentiate between the drones and the UFOs.
If you live in a place where UFOs are flying and you spend alot of time watching the sky at night your eyes will get used to seeing the UFOs and you will know one when you see it. Back in 2012 the sky where I live were inundated with UFOs. For 2 or 3 years I spent many a night watching them and trying to capture them on video. The UFOs became scarce in 2015 and nowadays I may have the occasional sighting but not like it was from 2012–2015.
The best sighting I ever had was in 2012 in the daytime when I saw a silver, saucer shaped craft. I saw a green fireball once. I chased a black triangular craft in my car that flew ahead of me and not much higher than the trees. Twice I saw huge orbs of light the size of a hot air balloon falling in the sky. I kept a diary of most of my sightings so I wouldn't forget them.
Physically telling the difference is difficult usually because most pictures and videos of objects in the sky are of such poor quality it is difficult to even tell what you are looking at.
You also have the problem that drones may exist in an almost infinite number of configurations from small almost undetectable in size objects to massive ones that fly up at the edge of the atmosphere.
You also have to take into consideration most people who use the term UFO are really thinking they are interested in a ETS (Extra Terrestrial Spacecraft) but don't understand the difference.
Extra Terrestrial Spacecraft (ETS) don't fly they vectate (vectored levitation) the term UFO does not apply. They are called CTVs (Celestial Tach One Vehicles) and/or Volutes. Tach One is the speed of light.
You would be far better served trying to understand what an actual ETS is than trying to look at pictures / videos and decide if they are drones or UFOs.
Search Google for the Extraterrestrial Disclosure Petition on the change(dot)org site to become a force for change. Currently we will not receive disclosure until the HET living among us complete the ETA (Extra Terrestrial Architecture).
The usual issue with these kinds of questions is imprecise use of language.
A UFO is an unidentified flying object. So anything you see flying around in the sky that you cannot identify ipso facto is a UFO. And although you cannot identify it, someone else may be able to identify it as a known aircraft transmitting IFF, it's rather subjective.
So what you need to do is to study the different kinds of drones that exist, along with all the other aircraft. I'd suggest getting some Jane's Guides. When you get something you cannot identify, you compare it with your reference material.
You may want to construct some sort of shape recognition software for flying objects.