endocrinologist vs specialist

endocrinologist and specialist both are nouns.

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

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

endocrinologist: physician who specializes in the diagnosis and treatment of conditions affecting the endocrine system
specialist: practices one branch of medicine

Other hypernyms of endocrinologist include medical specialist.

endocrinologist (noun)	specialist (noun)
physician who specializes in the diagnosis and treatment of conditions affecting the endocrine system	an expert who is devoted to one occupation or branch of learning
	practices one branch of medicine