nooks and crannies vs item

nooks and crannies and item both are nouns.

Word	Noun	Adjective	Verb	Adverb
nooks and crannies	Yes	No	No	No
item	Yes	No	No	Yes

As nouns, item is a hypernym of nooks and crannies; that is, item is a word with a broader meaning than nooks and crannies:

Other hypernyms of nooks and crannies include detail, point.

nooks and crannies (noun)	item (noun)
something remote	a whole individual unit; especially when included in a list or collection
	an isolated fact that is considered separately from the whole
	a distinct part that can be specified separately in a group of things that could be enumerated on a list
	an individual instance of a type of symbol
	a small part that can be considered separately from the whole

nooks and crannies (adverb)	item (adverb)
	(used when listing or enumerating items) also