LED vs crystal rectifier

LED and crystal rectifier both are nouns.

Word	Noun	Adjective	Verb	Adverb
LED	Yes	No	No	No
crystal rectifier	Yes	No	No	No

As nouns, crystal rectifier is a hypernym of LED; that is, crystal rectifier is a word with a broader meaning than LED:

LED: diode such that light emitted at a p-n junction is proportional to the bias current; color depends on the material used
crystal rectifier: a semiconductor that consists of a p-n junction

Other hypernyms of LED include diode, junction rectifier, semiconductor diode.

LED (noun)	crystal rectifier (noun)
diode such that light emitted at a p-n junction is proportional to the bias current; color depends on the material used	a semiconductor that consists of a p-n junction