memory device vs device

memory device and device both are nouns.

Word	Noun	Adjective	Verb	Adverb
memory device	Yes	No	No	No
device	Yes	No	No	No

As nouns, device is a hypernym of memory device; that is, device is a word with a broader meaning than memory device:

memory device (noun)	device (noun)
a device that preserves information for retrieval	any clever maneuver
	an instrumentality invented for a particular purpose
	an emblematic design (especially in heraldry)
	any ornamental pattern or design (as in embroidery)
	something in an artistic work designed to achieve a particular effect