beer barrel vs cask

beer barrel and cask both are nouns.

Word	Noun	Adjective	Verb	Adverb
beer barrel	Yes	No	No	No
cask	Yes	No	No	No

As nouns, cask is a hypernym of beer barrel; that is, cask is a word with a broader meaning than beer barrel:

Other hypernyms of beer barrel include barrel.

beer barrel (noun)	cask (noun)
a barrel that holds beer	a cylindrical container that holds liquids
	the quantity a cask will hold