Dr. vs MD

Dr. and MD both are nouns.

Word	Noun	Adjective	Verb	Adverb
Dr.	Yes	No	No	No
MD	Yes	No	No	No

As nouns, Dr. and MD are synonyms defined as:

Other synonyms of Dr. include doc, doctor, medico, physician.

Dr. (noun)	MD (noun)
a licensed medical practitioner	a doctor's degree in medicine
a person who holds Ph.D. degree (or the equivalent) from an academic institution	a Mid-Atlantic state; one of the original 13 colonies, with capital Annapolis
	a licensed medical practitioner