ROM vs computer memory

ROM and computer memory both are nouns.

Word	Noun	Adjective	Verb	Adverb
ROM	Yes	No	No	No
computer memory	Yes	No	No	No

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

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

Other hypernyms of ROM include computer storage, memory, memory board, storage, store.

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