If you use the expanded definition of engine (e.g., "search engine", where "engine" is mostly used as a synonym of "machine"), then neither is a subtype of the

If you use the expanded definition of engine (e.g., "search engine", where "engine" is mostly used as a synonym of "machine"), then neither is a subtype of the other - they just overlap occasionally. However, all engines producing motion would also be considered motors (what is under the hood of a classical ICE car is both an engine and a motor, and is just a motor in other Germanic languages), and most motors producing motors would not be referred to as engines (an EV does not have "electric engines"). So for the types of devices where you are likely going to have the discussion - things makings stuff move - motor is the supertype and engine is the subtype.