auto manufacturer vs car maker

auto manufacturer and car maker both are nouns.

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

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

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

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

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