kingmaker vs important person

kingmaker and important person both are nouns.

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

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

kingmaker: an important person who can bring leaders to power through the exercise of political influence
important person: a person whose actions and opinions strongly influence the course of events

Other hypernyms of kingmaker include influential person, personage.

kingmaker (noun)	important person (noun)
an important person who can bring leaders to power through the exercise of political influence	a person whose actions and opinions strongly influence the course of events