automobile factory vs auto factory

automobile factory and auto factory both are nouns.

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

As nouns, automobile factory and auto factory are synonyms defined as:

automobile factory and auto factory: a factory where automobiles are manufactured

Other synonyms of automobile factory include car factory.

automobile factory (noun)	auto factory (noun)
a factory where automobiles are manufactured	a factory where automobiles are manufactured