What is the difference between biscuit and bread wheat?

Biscuit and bread wheats differ in terms of the hardness of their grains and in the type of doughs which are made from their flour. Biscuit wheats are soft, which means special mills are required to extract the flour. Soft wheats in a conventional hard wheat (or bread wheat) mill would clog up sieves used to separate the white inner part of the grain called the endosperm from the rest of the grain.
The softness of biscuit flours means they only absorb small amounts of water when mixed into a dough. Doughs made with biscuit flours spread out sideways when baking, and so produce high quality biscuits.