beer barrel vs barrel

beer barrel and barrel both are nouns.

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

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

Other hypernyms of beer barrel include cask.

beer barrel (noun)	barrel (noun)
a barrel that holds beer	a cylindrical container that holds liquids
	a tube through which a bullet travels when a gun is fired
	any of various units of capacity
	the quantity that a barrel (of any size) will hold
	a bulging cylindrical shape; hollow with flat ends

beer barrel (verb)	barrel (verb)
	put in barrels