Engine is not only applicable to power generation device, but also refers to the whole machine including power device (such as gasoline engine and aeroengine). The engine was first born in Britain, so the concept of engine also originates from English, and its original meaning refers to the kind of "mechanical device that generates power".

The difference between diesel engine and other internal combustion engines (such as gasoline engine) is that the latter introduces the flammable mixture of air and vaporized or gaseous fuel into the cylinder and ignites it with an electric spark after appropriate compression, while the former does not use an ignition system, so it is often called a compression ignition engine. The fuel for diesel engines is graded and unrefined. Its disadvantages are high initial cost and large weight per horsepower, resulting in air pollution, running noise and vibration.