Danube River vs Union of Serbia and Montenegro

Danube River and Union of Serbia and Montenegro both are nouns.

Word	Noun	Adjective	Verb	Adverb
Danube River	Yes	No	No	No
Union of Serbia and Montenegro	Yes	No	No	No

Danube River (noun)	Union of Serbia and Montenegro (noun)
the 2nd longest European river (after the Volga); flows from southwestern Germany to the Black Sea	a mountainous republic in southeastern Europe bordering on the Adriatic Sea; formed from two of the six republics that made up Yugoslavia until 1992; Serbia and Montenegro were known as the Federal Republic of Yugoslavia until 2003 when they adopted the name of the Union of Serbia and Montenegro