zwieback vs Brussels biscuit

zwieback and Brussels biscuit both are nouns.

Word	Noun	Adjective	Verb	Adverb
zwieback	Yes	No	No	No
Brussels biscuit	Yes	No	No	No

As nouns, zwieback and Brussels biscuit are synonyms defined as:

zwieback and Brussels biscuit: slice of sweet raised bread baked again until it is brown and hard and crisp

Other synonyms of zwieback include rusk, twice-baked bread.

zwieback (noun)	Brussels biscuit (noun)
slice of sweet raised bread baked again until it is brown and hard and crisp	slice of sweet raised bread baked again until it is brown and hard and crisp