experimenter vs investigator

experimenter and investigator both are nouns.

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

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

Other hypernyms of experimenter include research worker, researcher.

experimenter (noun)	investigator (noun)
a research worker who conducts experiments	someone who investigates
a person who enjoys testing innovative ideas	a scientist who devotes himself to doing research
	a police officer who investigates crimes