military policeman vs MP

military policeman and MP both are nouns.

Word	Noun	Adjective	Verb	Adverb
military policeman	Yes	No	No	No
MP	Yes	No	No	No

As nouns, military policeman and MP are synonyms defined as:

military policeman and MP: a member of the military police who polices soldiers and guards prisoners

military policeman (noun)	MP (noun)
a member of the military police who polices soldiers and guards prisoners	a military corps that enforces discipline and guards prisoners
	a member of the military police who polices soldiers and guards prisoners