milk vs foodstuff

milk and foodstuff both are nouns.

Word	Noun	Adjective	Verb	Adverb
milk	Yes	No	Yes	No
foodstuff	Yes	No	No	No

As nouns, foodstuff is a hypernym of milk; that is, foodstuff is a word with a broader meaning than milk:

Other hypernyms of milk include food product.

milk (noun)	foodstuff (noun)
produced by mammary glands of female mammals for feeding their young	(usually plural) consumer goods sold by a grocer
a white nutritious liquid secreted by mammals and used as food by human beings	a substance that can be used or prepared for use as food
any of several nutritive milklike liquids

milk (verb)	foodstuff (verb)
take milk from female mammals
add milk to
exploit as much as possible