Appalachian Mountains vs chain of mountains

Appalachian Mountains and chain of mountains both are nouns.

Word	Noun	Adjective	Verb	Adverb
Appalachian Mountains	Yes	No	No	No
chain of mountains	Yes	No	No	No

Appalachian Mountains (noun)	chain of mountains (noun)
a mountain range in the eastern United States extending from Quebec to the Gulf of Mexico; a historic barrier to early westward expansion of the United States	a series of hills or mountains