East Coast vs East Coast of the United States

East Coast and East Coast of the United States both are nouns.

Word	Noun	Adjective	Verb	Adverb
East Coast	Yes	No	No	No
East Coast of the United States	Yes	No	No	No

As nouns, East Coast and East Coast of the United States are synonyms defined as:

East Coast and East Coast of the United States: the eastern seaboard of the United States (especially the strip between Boston and Washington D.C.)

East Coast (noun)	East Coast of the United States (noun)
the eastern seaboard of the United States (especially the strip between Boston and Washington D.C.)	the eastern seaboard of the United States (especially the strip between Boston and Washington D.C.)