carriage vs railway car

carriage and railway car both are nouns.

Word	Noun	Adjective	Verb	Adverb
carriage	Yes	No	No	No
railway car	Yes	No	No	No

As nouns, railway car is a hypernym of carriage; that is, railway car is a word with a broader meaning than carriage:

Other hypernyms of carriage include car, railcar, railroad car.

carriage (noun)	railway car (noun)
a vehicle with wheels drawn by one or more horses	a wheeled vehicle adapted to the rails of railroad
a railcar where passengers ride
a machine part that carries something else
a small vehicle with four wheels in which a baby or child is pushed around
characteristic way of bearing one's body