storage vs ROM

storage and ROM both are nouns.

Word	Noun	Adjective	Verb	Adverb
storage	Yes	No	No	No
ROM	Yes	No	No	No

As nouns, ROM is a hyponym of storage; that is, ROM is a word with a more specific, narrower meaning than storage:

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

storage (noun)	ROM (noun)
the commercial enterprise of storing goods and materials	(computer science) memory whose contents can be accessed and read but cannot be changed
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