light beer vs lager

light beer and lager both are nouns.

Word	Noun	Adjective	Verb	Adverb
light beer	Yes	No	No	No
lager	Yes	No	No	No

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

light beer: lager with reduced alcohol content
lager: a general term for beer made with bottom fermenting yeast (usually by decoction mashing); originally it was brewed in March or April and matured until September

Other hypernyms of light beer include lager beer.

light beer (noun)	lager (noun)
lager with reduced alcohol content	a camp defended by a circular formation of wagons
	a general term for beer made with bottom fermenting yeast (usually by decoction mashing); originally it was brewed in March or April and matured until September