brewer's grain vs residue

brewer's grain and residue both are nouns.

Word	Noun	Adjective	Verb	Adverb
brewer's grain	Yes	No	No	No
residue	Yes	No	No	No

As nouns, residue is a hypernym of brewer's grain; that is, residue is a word with a broader meaning than brewer's grain:

brewer's grain: the residue of malt and grain which remains in the mash-kettle after the mashing and lautering process.
residue: matter that remains after something has been removed

brewer's grain (noun)	residue (noun)
the residue of malt and grain which remains in the mash-kettle after the mashing and lautering process.	something left after other parts have been taken away
	matter that remains after something has been removed