redcap vs military policeman

redcap and military policeman both are nouns.

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

As nouns, military policeman is a hypernym of redcap; that is, military policeman is a word with a broader meaning than redcap:

redcap: a member of the military police in Britain
military policeman: a member of the military police who polices soldiers and guards prisoners

Other hypernyms of redcap include MP.

redcap (noun)	military policeman (noun)
a porter who helps passengers with their baggage at a railroad station	a member of the military police who polices soldiers and guards prisoners
a member of the military police in Britain