officer vs traffic cop

officer and traffic cop both are nouns.

Word	Noun	Adjective	Verb	Adverb
officer	Yes	No	Yes	No
traffic cop	Yes	No	No	No

As nouns, traffic cop is a hyponym of officer; that is, traffic cop is a word with a more specific, narrower meaning than officer:

officer (noun)	traffic cop (noun)
a member of a police force	a policeman who controls the flow of automobile traffic
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)	traffic cop (verb)
direct or command as an officer