draff vs spent grain

draff and spent grain both are nouns.

Word	Noun	Adjective	Verb	Adverb
draff	Yes	No	No	No
spent grain	Yes	No	No	No

As nouns, draff and spent grain are synonyms defined as:

draff and spent grain: the residue of malt and grain which remains in the mash-kettle after the mashing and lautering process.

Other synonyms of draff include brewer's grain.

draff (noun)	spent grain (noun)
the residue of malt and grain which remains in the mash-kettle after the mashing and lautering process.	the residue of malt and grain which remains in the mash-kettle after the mashing and lautering process.