optometrist vs specialist

optometrist and specialist both are nouns.

Word	Noun	Adjective	Verb	Adverb
optometrist	Yes	No	No	No
specialist	Yes	No	No	No

As nouns, specialist is a hypernym of optometrist; that is, specialist is a word with a broader meaning than optometrist:

optometrist: a person skilled in testing for defects of vision in order to prescribe corrective glasses
specialist: an expert who is devoted to one occupation or branch of learning

Other hypernyms of optometrist include specialiser, specializer.

optometrist (noun)	specialist (noun)
a person skilled in testing for defects of vision in order to prescribe corrective glasses	an expert who is devoted to one occupation or branch of learning
	practices one branch of medicine