carriage vs roadster

carriage and roadster both are nouns.

Word	Noun	Adjective	Verb	Adverb
carriage	Yes	No	No	No
roadster	Yes	No	No	No

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

carriage (noun)	roadster (noun)
a vehicle with wheels drawn by one or more horses	a small lightweight carriage; drawn by a single horse
a railcar where passengers ride	an open automobile having a front seat and a rumble seat
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