Muskhogean vs American Indian

Muskhogean and American Indian both are nouns.

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

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

Muskhogean: a family of North American Indian languages spoken in the southeastern United States
American Indian: any of the languages spoken by Amerindians

Muskhogean (noun)	American Indian (noun)
a family of North American Indian languages spoken in the southeastern United States	any of the languages spoken by Amerindians
a member of any of the peoples formerly living in southeastern United States and speaking Muskhogean languages