therapist vs expert

therapist and expert both are nouns.

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

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

therapist (noun)	expert (noun)
a person skilled in a particular type of therapy	a person with special knowledge or ability who performs skillfully

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