houseman vs MD

houseman and MD both are nouns.

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

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

houseman: an advanced student or graduate in medicine gaining supervised practical experience
MD: a licensed medical practitioner

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

houseman (noun)	MD (noun)
an advanced student or graduate in medicine gaining supervised practical experience	a doctor's degree in medicine
	a Mid-Atlantic state; one of the original 13 colonies, with capital Annapolis
	a licensed medical practitioner