chain of mountains vs mountain chain

chain of mountains and mountain chain both are nouns.

Word	Noun	Adjective	Verb	Adverb
chain of mountains	Yes	No	No	No
mountain chain	Yes	No	No	No

As nouns, chain of mountains and mountain chain are synonyms defined as:

Other synonyms of chain of mountains include chain, mountain range, range, range of mountains.

chain of mountains (noun)	mountain chain (noun)
a series of hills or mountains	a series of hills or mountains