power structure vs hierarchy

power structure and hierarchy both are nouns.

Word	Noun	Adjective	Verb	Adverb
power structure	Yes	No	No	No
hierarchy	Yes	No	No	No

As nouns, power structure and hierarchy are synonyms defined as:

power structure and hierarchy: the organization of people at different ranks in an administrative body

Other synonyms of power structure include pecking order.

power structure (noun)	hierarchy (noun)
the organization of people at different ranks in an administrative body	a series of ordered groupings of people or things within a system
	the organization of people at different ranks in an administrative body