mountain chain vs chain of mountains

mountain chain and chain of mountains both are nouns.

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

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

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

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