auto maker vs car maker

auto maker and car maker both are nouns.

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

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

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

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

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