inspector vs investigator

inspector and investigator both are nouns.

Word	Noun	Adjective	Verb	Adverb
inspector	Yes	No	No	No
investigator	Yes	No	No	No

As nouns, investigator is a hypernym of inspector; that is, investigator is a word with a broader meaning than inspector:

inspector (noun)	investigator (noun)
an investigator who observes carefully	someone who investigates
a high ranking police officer	a scientist who devotes himself to doing research
	a police officer who investigates crimes