Mashed grains are grains that have been crushed or sliced with a hammer mill while they are still wet with starch inside them so that they break down easier during fermentation, which helps produce sugars that yeast will convert into alcohol during fermentation. The malted grain on the other hand is barley or wheat that has been allowed to germinate by soaking the grain in water and storing it for some time. This produces fermentable sugars from the starch in your grain.