major power vs superpower

major power and superpower both are nouns.

Word	Noun	Adjective	Verb	Adverb
major power	Yes	No	No	No
superpower	Yes	No	No	No

As nouns, major power and superpower are synonyms defined as:

major power and superpower: a state powerful enough to influence events throughout the world

Other synonyms of major power include great power, power, world power.

major power (noun)	superpower (noun)
a state powerful enough to influence events throughout the world	a state powerful enough to influence events throughout the world