memory board vs memory device

memory board and memory device both are nouns.

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

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

Other hypernyms of memory board include computer hardware, hardware, storage device.

memory board (noun)	memory device (noun)
an electronic memory device	a device that preserves information for retrieval