zwieback

As nouns the difference between zwieback and hardtack

is that zwieback is zwieback (toasted sweetened bread) while hardtack is (nautical) a large, hard biscuit made from unleavened flour and water; formerly used as a long-term staple food aboard ships.

As nouns the difference between taxonomy and zwieback

is that taxonomy is the science or the technique used to make a classification while zwieback is zwieback (toasted sweetened bread).

As nouns the difference between zwieback and biscotti

is that zwieback is a usually sweetened bread enriched with eggs that is baked and then sliced and toasted until dry and crisp while biscotti is a hard, usually nut-flavored biscuit, derived from the Tuscan cantucci