carriage vs chair car

carriage and chair car both are nouns.

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

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

carriage: a railcar where passengers ride
chair car: a passenger car for day travel; you pay extra fare for individual chairs

carriage (noun)	chair car (noun)
a vehicle with wheels drawn by one or more horses	a passenger car for day travel; you pay extra fare for individual chairs
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