case officer vs secret agent

case officer and secret agent both are nouns.

Word	Noun	Adjective	Verb	Adverb
case officer	Yes	No	No	No
secret agent	Yes	No	No	No

As nouns, secret agent is a hypernym of case officer; that is, secret agent is a word with a broader meaning than case officer:

case officer: an operative who also serves as an official staffer of an intelligence service
secret agent: a person secretly employed in espionage for a government

Other hypernyms of case officer include intelligence agent, intelligence officer, operative.

case officer (noun)	secret agent (noun)
an operative who also serves as an official staffer of an intelligence service	a person secretly employed in espionage for a government