auto vs motorcar

auto and motorcar both are nouns.

Word	Noun	Adjective	Verb	Adverb
auto	Yes	No	No	No
motorcar	Yes	No	No	No

As nouns, auto and motorcar are synonyms defined as:

auto and motorcar: a motor vehicle with four wheels; usually propelled by an internal combustion engine

Other synonyms of auto include automobile, car, machine.

auto (noun)	motorcar (noun)
a motor vehicle with four wheels; usually propelled by an internal combustion engine	a motor vehicle with four wheels; usually propelled by an internal combustion engine