posse comitatus vs police force

posse comitatus and police force both are nouns.

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

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

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

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