auto vs automobile

auto and automobile both are nouns.

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

As nouns, auto and automobile are synonyms defined as:

auto and automobile: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other synonyms of auto include car, machine, motorcar.

auto (noun)	automobile (noun)
a motor vehicle with four wheels; usually propelled by an internal combustion engine	a motor vehicle with four wheels; usually propelled by an internal combustion engine

auto (verb)	automobile (verb)
	travel in an automobile