two-seater vs auto

two-seater and auto both are nouns.

Word	Noun	Adjective	Verb	Adverb
two-seater	Yes	No	No	No
auto	Yes	No	No	No

As nouns, auto is a hypernym of two-seater; that is, auto is a word with a broader meaning than two-seater:

two-seater: an open automobile having a front seat and a rumble seat
auto: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of two-seater include automobile, car, machine, motorcar.

two-seater (noun)	auto (noun)
an open automobile having a front seat and a rumble seat	a motor vehicle with four wheels; usually propelled by an internal combustion engine