sacred cow vs important person

sacred cow and important person both are nouns.

Word	Noun	Adjective	Verb	Adverb
sacred cow	Yes	No	No	No
important person	Yes	No	No	No

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

sacred cow: a person unreasonably held to be immune to criticism
important person: a person whose actions and opinions strongly influence the course of events

Other hypernyms of sacred cow include influential person, personage.

sacred cow (noun)	important person (noun)
a person unreasonably held to be immune to criticism	a person whose actions and opinions strongly influence the course of events