boffin vs investigator

boffin and investigator both are nouns.

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

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

boffin: (British slang) a scientist or technician engaged in military research
investigator: a scientist who devotes himself to doing research

Other hypernyms of boffin include research worker, researcher.

boffin (noun)	investigator (noun)
(British slang) a scientist or technician engaged in military research	someone who investigates
	a scientist who devotes himself to doing research
	a police officer who investigates crimes