officer vs police officer

officer and police officer both are nouns.

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

As nouns, officer and police officer are synonyms defined as:

officer (noun)	police officer (noun)
a member of a police force	a member of a police force
someone who is appointed or elected to an office and who holds a position of trust
any person in the armed services who holds a position of authority or command
a person authorized to serve in a position of authority on a vessel

officer (verb)	police officer (verb)
direct or command as an officer