superpower vs nation

superpower and nation both are nouns.

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

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

superpower: a state powerful enough to influence events throughout the world
nation: a politically organized body of people under a single government

Other hypernyms of superpower include body politic, commonwealth, country, land, res publica, state.

superpower (noun)	nation (noun)
a state powerful enough to influence events throughout the world	a politically organized body of people under a single government
	the people who live in a nation or country
	a federation of tribes (especially Native American tribes)