I've been thinking about how we use language so informally these days. It's like the difference between a cell and a battery. Technically, when multiple cells are put together, it's a battery of cells. The term "battery" refers to the collection ... like a missile battery. Likewise, many people use the terms motor, engine and even generator as synonyms. But they're not quite the same. I've taken the following from a few different sources. A motor is a device that changes electrical energy into mechanical energy, while an engine is a device, which converts chemical energy or heat energy into mechanical energy. Therefore, motors are electric, while engines are powered by pressure or combustion. Your typical gasoline engine has an electrical starter motor. Generators are devices that convert chemical energy into electrical energy. My parents fleetwood rv has a diesel generator to run the AC while they are off the grid.