vodka vs hard liquor

vodka and hard liquor both are nouns.

Word	Noun	Adjective	Verb	Adverb
vodka	Yes	No	No	No
hard liquor	Yes	No	No	No

As nouns, hard liquor is a hypernym of vodka; that is, hard liquor is a word with a broader meaning than vodka:

Other hypernyms of vodka include booze, hard drink, John Barleycorn, liquor, spirits, strong drink.

vodka (noun)	hard liquor (noun)
unaged colorless liquor originating in Russia	an alcoholic beverage that is distilled rather than fermented