A propeller engine uses a rotating propeller to generate thrust, while a jet engine uses a high-speed jet of exhaust gases to produce thrust. Propeller engines are typically found on smaller aircraft and operate at lower speeds and altitudes, while jet engines are used on larger aircraft and can operate at higher speeds and altitudes. Propeller engines are generally less fuel-efficient than jet engines, but can be more reliable and have lower maintenance costs. Jet engines provide greater power and speed, but are more complex and expensive to operate and maintain.