sierra vs chain of mountains

sierra and chain of mountains both are nouns.

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

As nouns, chain of mountains is a hypernym of sierra; that is, chain of mountains is a word with a broader meaning than sierra:

sierra: a range of mountains (usually with jagged peaks and irregular outline)
chain of mountains: a series of hills or mountains

Other hypernyms of sierra include chain, mountain chain, mountain range, range, range of mountains.

sierra (noun)	chain of mountains (noun)
a Spanish mackerel of western North America	a series of hills or mountains
a range of mountains (usually with jagged peaks and irregular outline)