posse comitatus vs police

posse comitatus and police both are nouns.

Word	Noun	Adjective	Verb	Adverb
posse comitatus	Yes	No	No	No
police	Yes	No	Yes	No

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

Other hypernyms of posse comitatus include constabulary, law, police force.

posse comitatus (noun)	police (noun)
a temporary police force	the force of policemen and officers

posse comitatus (verb)	police (verb)
	maintain the security of by carrying out a patrol