food product vs foodstuff

food product and foodstuff both are nouns.

Word	Noun	Adjective	Verb	Adverb
food product	Yes	No	No	No
foodstuff	Yes	No	No	No

As nouns, food product and foodstuff are synonyms defined as:

food product and foodstuff: a substance that can be used or prepared for use as food

food product (noun)	foodstuff (noun)
a substance that can be used or prepared for use as food	(usually plural) consumer goods sold by a grocer
	a substance that can be used or prepared for use as food