Power train and Reduction gear

Power train noun - Wheelwork consisting of a connected set of rotating gears by which force is transmitted or motion or torque is changed.

Reduction gear and power train are semantically related. In some cases you can replace phrase "Reduction gear" with "Power train", this phrases are similar.

Reduction gear noun - Gearing that reduces an input speed to a slower output speed.

Power train and reduction gear are semantically related. Sometimes you can use "Power train" instead a noun phrase "Reduction gear".