eli5: What (if any) is the difference between an engine and a motor?

Question

I’ve heard these words used interchangeably over the years, with engine being more prevalent. Is there any difference? Why is a small gas-driven device like a lawnmower commonly said to have a motor, while what is under the hood of a car is almost always referred to as an engine?

In: 160

Answer 1

An engine is a machine that converts thermal energy into mechanical energy to produce forward motion. So an old steam train would have their entire unit that provided power called an engine. A motor is a rotating machine that transforms electricity energy into mechanical energy. Over the years the definitions have become somewhat ambiguous and the two terms tend to be interchanged but they do mean two very different things.