Native American vs Amerindian

Native American and Amerindian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Native American	Yes	Yes	No	No
Amerindian	Yes	No	No	No

As nouns, Native American and Amerindian are synonyms defined as:

Native American and Amerindian: any member of the peoples living in North or South America before the Europeans arrived

Native American (noun)	Amerindian (noun)
any member of the peoples living in North or South America before the Europeans arrived	any member of the peoples living in North or South America before the Europeans arrived

Native American (adjective)	Amerindian (adjective)
of or pertaining to Native Americans or their culture or languages