hierarchy vs power structure

hierarchy and power structure both are nouns.

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

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

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

Other synonyms of hierarchy include pecking order.

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