The major distinction between diesel and gas lies in the type of ignition. While gas engines operate on spark ignition, diesel engines employ compression ignition for igniting the fuel. With compression, the air is drawn into the engine and subjected to high compression that heats it up. The result is a very high temperature in the engine, much high than that of gas engines.

In diesel engines, air and fuel are both infused into the engine at different stages, as opposed to gas where a mixture of air and gas are introduced. The fuel is injected into the diesel using an injector where in a gas engine, a carburetor is used for this very purpose.