specialist vs doc

specialist and doc both are nouns.

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

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

Other hypernyms of specialist include doctor, Dr., MD, medico, physician.

specialist (noun)	doc (noun)
an expert who is devoted to one occupation or branch of learning	a licensed medical practitioner
practices one branch of medicine