point duty vs Great Britain

point duty and Great Britain both are nouns.

Word	Noun	Adjective	Verb	Adverb
point duty	Yes	No	No	No
Great Britain	Yes	No	No	No

point duty (noun)	Great Britain (noun)
the control of traffic by a policeman stationed at an intersection	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