auto maker vs carmaker

auto maker and carmaker both are nouns.

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

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

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

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

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