tribe vs nation

tribe and nation both are nouns.

Word	Noun	Adjective	Verb	Adverb
tribe	Yes	No	No	No
nation	Yes	No	No	No

As nouns, nation is a hypernym of tribe; that is, nation is a word with a broader meaning than tribe:

tribe (noun)	nation (noun)
a social division of (usually preliterate) people	a politically organized body of people under a single government
a federation (as of American Indians)	the people who live in a nation or country
group of people related by blood or marriage	a federation of tribes (especially Native American tribes)
(biology) a taxonomic category between a genus and a subfamily