greengrocer vs Great Britain

greengrocer and Great Britain both are nouns.

Word	Noun	Adjective	Verb	Adverb
greengrocer	Yes	No	No	No
Great Britain	Yes	No	No	No

greengrocer (noun)	Great Britain (noun)
a grocer who sells fresh fruits and vegetables	an island comprising England and Scotland and Wales
	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