storage space vs closet

storage space and closet both are nouns.

Word	Noun	Adjective	Verb	Adverb
storage space	Yes	No	No	No
closet	Yes	No	Yes	No

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

Other hyponyms of storage space include cache, cellar, wine cellar, cupboard, drawer, cellar, root cellar, stacks.

storage space (noun)	closet (noun)
the area in any structure that provides space for storage	a small private room for study or prayer
	a toilet in Britain
	a tall piece of furniture that provides storage space for clothes; has a door and rails or hooks for hanging clothes
	a small room (or recess) or cabinet used for storage space

storage space (verb)	closet (verb)
	confine to a small space, as for intensive work