American Indian vs American Indian language

American Indian and American Indian language both are nouns.

Word	Noun	Adjective	Verb	Adverb
American Indian	Yes	No	No	No
American Indian language	Yes	No	No	No

As nouns, American Indian and American Indian language are synonyms defined as:

American Indian and American Indian language: any of the languages spoken by Amerindians

American Indian (noun)	American Indian language (noun)
any of the languages spoken by Amerindians	any of the languages spoken by Amerindians