major power vs world power

major power and world power both are nouns.

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

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

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

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

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