FSD or Full Self Driving is the thing that drives the car all by itself. If you are not in the beta, it can only be activated on highways.
So basically this guy plowed a red light and cruise control and killed someone.
The desire to name it "autopilot" stems from a desire for positive marketing, not a desire for technical correctness. (And certainly not from a desire to accurately convey limitations to users!)
An autopilot in a commercial passenger aircraft is fully capable of controlling the plane after takeoff, landing, and taxiing up to the destination gate. Or in other words, after takeoff, it is fully capable of controlling the plane without any input from the pilot.
So, when Tesla advertises their cruise control as "autopilot" they are overstating the abilities of autopilot mode if they put in the fine print that a human actually is responsible for controlling the vehicle and that autopilot is just a glorified cruise control.
Flight autopilot generally warns when terrain or traffic is advancing. You can also program routes, etc. on the flight management computer which connects and controls autopilot. Many planes even autoland in certain conditions.
Growing up, I spent a lot of time on boats. The county I grew up in was primarily a fishing/crabbing economy. Autopilot on boats is like this. It maintains a compass heading. At no point does it steer you around obstacles or react to anything other than changes in the compass heading induced by drift, waves, currents, wind, etc.