horseless carriage vs motorcar

horseless carriage and motorcar both are nouns.

Word	Noun	Adjective	Verb	Adverb
horseless carriage	Yes	No	No	No
motorcar	Yes	No	No	No

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

horseless carriage: an early term for an automobile
motorcar: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of horseless carriage include auto, automobile, car, machine.

horseless carriage (noun)	motorcar (noun)
an early term for an automobile	a motor vehicle with four wheels; usually propelled by an internal combustion engine