auto manufacturer vs carmaker

auto manufacturer and carmaker both are nouns.

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

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

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

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

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