First of all, we need to know many deaths occur a year from those two. In the year 2021, the were 171 deaths caused by plane crashes, while cars annually cause 1.3 MILLION deaths per year. Yes, you saw it right, million. but again, more quantity of cars.
This is usually opinion-wised, but what if I tell you there’s an answer? According to David Ropeik, a Harvard professor, the chances of dying in a car is 1 in 5,000, but dying in a plane crash is 1 in 11,000,000. This is probably due to planes literally designed to have multiple safety features such as flame-resistant seats, oxygen masks, secret toilet locks, and if you didn’t know, plane windows being a circle is also a “kind of” safety since square windows would make the plane crash because of the weak edges.
But if you look at cars, safety features are present as well, like seatbelts (duh), airbags, and antilock brakes are in literally every car, but blind-spot monitoring and active head restraints aren’t found in every car you see.
On top of those, you can always trust the person flying the plane, the pilot, as they literally have a license and have trained for years, while cars are basically a “quick device” for slightly far places, so not all people can be trusted while driving.
So, airplanes are safer I guess.