Great Britain vs sponge bag

Great Britain and sponge bag both are nouns.

Word	Noun	Adjective	Verb	Adverb
Great Britain	Yes	No	No	No
sponge bag	Yes	No	No	No

Great Britain (noun)	sponge bag (noun)
an island comprising England and Scotland and Wales	a waterproof bag for holding bathrooms items (soap and toothpaste etc.) when you are travelling
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