carriage vs dining car

carriage and dining car both are nouns.

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

As nouns, dining car is a hyponym of carriage; that is, dining car is a word with a more specific, narrower meaning than carriage:

carriage (noun)	dining car (noun)
a vehicle with wheels drawn by one or more horses	a passenger car where food is served in transit
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