hematology vs medical specialty

hematology and medical specialty both are nouns.

Word	Noun	Adjective	Verb	Adverb
hematology	Yes	No	No	No
medical specialty	Yes	No	No	No

As nouns, medical specialty is a hypernym of hematology; that is, medical specialty is a word with a broader meaning than hematology:

hematology: the branch of medicine that deals with diseases of the blood and blood-forming organs
medical specialty: the branches of medical science that deal with nonsurgical techniques

Other hypernyms of hematology include medicine.

hematology (noun)	medical specialty (noun)
the branch of medicine that deals with diseases of the blood and blood-forming organs	the branches of medical science that deal with nonsurgical techniques