cellar vs root cellar

cellar and root cellar both are nouns.

Word	Noun	Adjective	Verb	Adverb
cellar	Yes	No	No	No
root cellar	Yes	No	No	No

As nouns, cellar and root cellar are synonyms defined as:

cellar (noun)	root cellar (noun)
the lowermost portion of a structure partly or wholly below ground level; often used for storage	an excavation where root vegetables are stored
storage space where wines are stored
an excavation where root vegetables are stored