lumber room vs storage room

lumber room and storage room both are nouns.

Word	Noun	Adjective	Verb	Adverb
lumber room	Yes	No	No	No
storage room	Yes	No	No	No

As nouns, storage room is a hypernym of lumber room; that is, storage room is a word with a broader meaning than lumber room:

lumber room: a storeroom in a house where odds and ends can be stored (especially furniture)
storage room: a room in which things are stored

Other hypernyms of lumber room include storeroom, stowage.

lumber room (noun)	storage room (noun)
a storeroom in a house where odds and ends can be stored (especially furniture)	a room in which things are stored