inquiry agent vs PI

inquiry agent and PI both are nouns.

Word	Noun	Adjective	Verb	Adverb
inquiry agent	Yes	No	No	No
PI	Yes	No	No	No

As nouns, PI is a hypernym of inquiry agent; that is, PI is a word with a broader meaning than inquiry agent:

inquiry agent: a private detective
PI: someone who can be employed as a detective to collect information and assist in criminal investigations

Other hypernyms of inquiry agent include operative, private detective, private eye, private investigator, shamus, sherlock.

inquiry agent (noun)	PI (noun)
a private detective	an antiviral drug used against HIV; interrupts HIV replication by binding and blocking HIV protease; often used in combination with other drugs
	someone who can be employed as a detective to collect information and assist in criminal investigations
	the scientist in charge of an experiment or research project