read-only memory vs storage

read-only memory and storage both are nouns.

Word	Noun	Adjective	Verb	Adverb
read-only memory	Yes	No	No	No
storage	Yes	No	No	No

As nouns, storage is a hypernym of read-only memory; that is, storage is a word with a broader meaning than read-only memory:

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

Other hypernyms of read-only memory include computer memory, computer storage, memory, memory board, store.

read-only memory (noun)	storage (noun)
(computer science) memory whose contents can be accessed and read but cannot be changed	the commercial enterprise of storing goods and materials
	the act of storing something
	depositing in a warehouse
	a depository for goods
	an electronic memory device
	(computer science) the process of storing information in a computer memory or on a magnetic tape or disk