car manufacturer vs auto manufacturer

car manufacturer and auto manufacturer both are nouns.

Word	Noun	Adjective	Verb	Adverb
car manufacturer	Yes	No	No	No
auto manufacturer	Yes	No	No	No

As nouns, car manufacturer and auto manufacturer are synonyms defined as:

car manufacturer and auto manufacturer: a business engaged in the manufacture of automobiles

Other synonyms of car manufacturer include auto maker, automaker, car maker, carmaker.

car manufacturer (noun)	auto manufacturer (noun)
a business engaged in the manufacture of automobiles	a business engaged in the manufacture of automobiles