lie detector vs polygraph

lie detector and polygraph both are nouns.

Word	Noun	Adjective	Verb	Adverb
lie detector	Yes	No	No	No
polygraph	Yes	No	No	No

As nouns, polygraph is a hypernym of lie detector; that is, polygraph is a word with a broader meaning than lie detector:

lie detector: a polygraph that records bodily changes sometimes associated with lying
polygraph: a medical instrument that records several physiological processes simultaneously (e.g., pulse rate and blood pressure and respiration and perspiration)

lie detector (noun)	polygraph (noun)
a polygraph that records bodily changes sometimes associated with lying	a medical instrument that records several physiological processes simultaneously (e.g., pulse rate and blood pressure and respiration and perspiration)