This is the most complicated subject I’ve ever tackled. I can’t even begin to explain how complex this topic is. The problem is that the term “ufo” is used to describe any non-human being, but the term “drone” is used to describe any aircraft, regardless of its technological capabilities.
The problem is that the term drone is only used to describe aircraft that fly on a human-powered, human-made drone. That drone can be anything, including satellites, helicopters, or autonomous vehicles—and even a robot that can carry a payload. This means that unmanned aircraft are often designed for the human-powered nature of their mission, but unlike a human, they may not be so efficient as to render the mission useless.
It’s not just the term drone that has an association with bad guys. In the movie Terminator 2, the Terminator has a robotic arm that uses a human brain to operate. It’s not clear if the Terminator’s brain is the same as a human’s or just a part of the machine.