loaner vs auto

loaner and auto both are nouns.

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

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

loaner: a car that is lent as a replacement for one that is under repair
auto: a motor vehicle with four wheels; usually propelled by an internal combustion engine

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

loaner (noun)	auto (noun)
a car that is lent as a replacement for one that is under repair	a motor vehicle with four wheels; usually propelled by an internal combustion engine
someone who lends money or gives credit in business matters