sleeping car vs carriage

sleeping car and carriage both are nouns.

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

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

Other hypernyms of sleeping car include coach, passenger car.

sleeping car (noun)	carriage (noun)
a passenger car that has berths for sleeping	a vehicle with wheels drawn by one or more horses
	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