Great Britain vs potboy

Great Britain and potboy both are nouns.

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

Great Britain (noun)	potboy (noun)
an island comprising England and Scotland and Wales	a worker in an inn or public house who serves customers and does various chores
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