range of mountains vs mountain chain

range of mountains and mountain chain both are nouns.

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

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

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

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