Drive-train typically refers to the components that transmit power from a vehicle's engine to its wheels. However, this term is often used interchangeably with other similar terms, such as powertrain, driveline, and propulsion system. The powertrain includes all the components that transfer power from the engine to the wheels, including the transmission, driveshaft, and differential. Driveline encompasses the driveshaft and axles and is responsible for connecting the engine to the wheels. Propulsion system is a broader term that includes any components that generate propulsion, such as engines, motors, and power systems. Ultimately, these terms all refer to the vital components that help vehicles move forward on the road.