nihil vs nil

nihil and nil both are nouns.

Word	Noun	Adjective	Verb	Adverb
nihil	Yes	No	No	No
nil	Yes	No	No	No

As nouns, nil is a hypernym of nihil; that is, nil is a word with a broader meaning than nihil:

nihil: (Latin) nil; nothing (as used by a sheriff after an unsuccessful effort to serve a writ)
nil: a quantity of no importance; thing (object:), singular, negative pronoun; pronoun, thing, singular; quantifier: negative existential

Other hypernyms of nihil include aught, cipher, cypher, goose egg, nada, naught, nix, nothing, null, zero, zilch, zip, zippo.

nihil (noun)	nil (noun)
(Latin) nil; nothing (as used by a sheriff after an unsuccessful effort to serve a writ)	a quantity of no importance; thing (object:), singular, negative pronoun; pronoun, thing, singular; quantifier: negative existential