superpower vs major power

superpower and major power both are nouns.

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

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

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

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

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