sierra vs range of mountains

sierra and range of mountains both are nouns.

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

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

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

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

sierra (noun)	range 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)