Injun vs Native American

Injun and Native American both are nouns.

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

As nouns, Native American is a hypernym of Injun; that is, Native American is a word with a broader meaning than Injun:

Injun: (slang) offensive term for Native Americans
Native American: any member of the peoples living in North or South America before the Europeans arrived

Other hypernyms of Injun include Amerindian.

Injun (noun)	Native American (noun)
(slang) offensive term for Native Americans	any member of the peoples living in North or South America before the Europeans arrived

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