Hard red winter and hard red spring contain the highest percentages of protein are most often used in goods requiring size, like breads and rolls.
Hard white and soft white contain the lowest percentages of protein and best suited for baked goods like cakes, cookies, crackers, pastries and muffins.
Soft red winter is often used in blatantly obvious brown crackers and flat breads. These are often marketed as “whole grain” crackers.
Wheat varieties are called "clean," "white," or "brown" or "hard" if they have high gluten content, and they are called "soft" or "weak" flour if gluten content is low. Hard flour, or bread flour, is high in gluten, with 12% to 14% gluten content, and has elastic toughness that holds its shape well once baked.