East Coast of the United States vs East Coast

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

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

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

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

East Coast of the United States (noun)	East Coast (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.)