NATO vs U.K.

NATO and U.K. both are nouns.

Word	Noun	Adjective	Verb	Adverb
NATO	Yes	No	No	No
U.K.	Yes	No	No	No

NATO (noun)	U.K. (noun)
an international organization created in 1949 by the North Atlantic Treaty for purposes of collective security	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