constable vs police officer

constable and police officer both are nouns.

Word	Noun	Adjective	Verb	Adverb
constable	Yes	No	No	No
police officer	Yes	No	No	No

As nouns, police officer is a hypernym of constable; that is, police officer is a word with a broader meaning than constable:

Other hypernyms of constable include officer.

constable (noun)	police officer (noun)
a lawman with less authority and jurisdiction than a sheriff	a member of a police force
a police officer of the lowest rank