The difference between Locomotive and Rolling stock

Locomotive as a noun (rail transport):

The power unit of a train that pulls the coaches or wagons.

Locomotive as a noun (rare):

A traction engine

Locomotive as a noun (slang):

A cheer characterized by a slow beginning and a progressive increase in speed

Locomotive as a noun (economics):

A country which drives the world economy by having a high level of imports. (i.e. The United States).

Locomotive as an adjective:

of or relating to locomotion

Locomotive as an adjective:

of or relating to the power unit of a train which does not carry passengers or freight itself

Rolling stock as a noun (railroads, uncountable, collectively):

All vehicles that move on a railway, powered or unpowered.

Rolling stock as a noun (countable, less common):

Any such vehicle.