estimator vs expert

estimator and expert both are nouns.

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

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

estimator (noun)	expert (noun)
an expert at calculation (or at operating calculating machines)	a person with special knowledge or ability who performs skillfully

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