superstar vs expert

superstar and expert both are nouns.

Word	Noun	Adjective	Verb	Adverb
superstar	Yes	No	No	No
expert	Yes	Yes	No	No

As nouns, expert is a hypernym of superstar; that is, expert is a word with a broader meaning than superstar:

superstar (noun)	expert (noun)
someone who is dazzlingly skilled in any field	a person with special knowledge or ability who performs skillfully

superstar (adjective)	expert (adjective)
	having or showing knowledge and skill and aptitude
	of or relating to or requiring special knowledge to be understood