fixed storage vs memory board

fixed storage and memory board both are nouns.

Word	Noun	Adjective	Verb	Adverb
fixed storage	Yes	No	No	No
memory board	Yes	No	No	No

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

fixed storage: (computer science) memory whose contents can be accessed and read but cannot be changed
memory board: an electronic memory device

Other hypernyms of fixed storage include computer memory, computer storage, memory, storage, store.

fixed storage (noun)	memory board (noun)
(computer science) memory whose contents can be accessed and read but cannot be changed	an electronic memory device