wagon vs auto

wagon and auto both are nouns.

Word	Noun	Adjective	Verb	Adverb
wagon	Yes	No	No	No
auto	Yes	No	No	No

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

wagon: a car that has a long body and rear door with space behind rear seat
auto: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other hypernyms of wagon include automobile, car, machine, motorcar.

wagon (noun)	auto (noun)
any of various kinds of wheeled vehicles drawn by an animal or a tractor	a motor vehicle with four wheels; usually propelled by an internal combustion engine
a car that has a long body and rear door with space behind rear seat
van used by police to transport prisoners
a child's four-wheeled toy cart sometimes used for coasting