GP vs MD

GP and MD both are nouns.

Word	Noun	Adjective	Verb	Adverb
GP	Yes	No	No	No
MD	Yes	No	No	No

As nouns, MD is a hypernym of GP; that is, MD is a word with a broader meaning than GP:

Other hypernyms of GP include doc, doctor, Dr., medico, physician.

GP (noun)	MD (noun)
a physician who is not a specialist but treats all illnesses	a doctor's degree in medicine
	a Mid-Atlantic state; one of the original 13 colonies, with capital Annapolis
	a licensed medical practitioner