powerbroker vs important person

powerbroker and important person both are nouns.

Word	Noun	Adjective	Verb	Adverb
powerbroker	Yes	No	No	No
important person	Yes	No	No	No

As nouns, important person is a hypernym of powerbroker; that is, important person is a word with a broader meaning than powerbroker:

powerbroker: a person who is important by virtue of the people or votes they control
important person: a person whose actions and opinions strongly influence the course of events

Other hypernyms of powerbroker include influential person, personage.

powerbroker (noun)	important person (noun)
a person who is important by virtue of the people or votes they control	a person whose actions and opinions strongly influence the course of events