mythologist vs expert

mythologist and expert both are nouns.

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

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

mythologist (noun)	expert (noun)
an expert on mythology	a person with special knowledge or ability who performs skillfully

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