SUV vs auto

SUV and auto both are nouns.

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

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

SUV: a high-performance four-wheel drive car built on a truck chassis
auto: a motor vehicle with four wheels; usually propelled by an internal combustion engine

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

SUV (noun)	auto (noun)
a high-performance four-wheel drive car built on a truck chassis	a motor vehicle with four wheels; usually propelled by an internal combustion engine