U.K. vs sponge bag

U.K. and sponge bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
U.K.	Yes	No	No	No
sponge bag	Yes	No	No	No

U.K. (noun)	sponge bag (noun)
a monarchy in northwestern Europe occupying most of the British Isles; divided into England and Scotland and Wales and Northern Ireland; `Great Britain' is often used loosely to refer to the United Kingdom	a waterproof bag for holding bathrooms items (soap and toothpaste etc.) when you are travelling