electric automobile vs auto

electric automobile and auto both are nouns.

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

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

electric automobile: a car that is powered by electricity
auto: a motor vehicle with four wheels; usually propelled by an internal combustion engine

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

electric automobile (noun)	auto (noun)
a car that is powered by electricity	a motor vehicle with four wheels; usually propelled by an internal combustion engine