beer vs draught beer

beer and draught beer both are nouns.

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

As nouns, draught beer is a hyponym of beer; that is, draught beer is a word with a more specific, narrower meaning than beer:

beer: a general name for alcoholic beverages made by fermenting a cereal (or mixture of cereals) flavored with hops
draught beer: beer drawn from a keg

Other hyponyms of beer include draft beer, suds, lager, lager beer, ale.

beer (noun)	draught beer (noun)
a general name for alcoholic beverages made by fermenting a cereal (or mixture of cereals) flavored with hops	beer drawn from a keg