Specialty grains are used to adjust the beer’s flavor profile and looks. They include less in the way of sugars but have a greater influence on the color of the beer. They can also add subtle flavors to the beer, or if you want to take it far enough, they can provide a serious change in flavor.
Adjunct grains are unmalted grains (such as corn, rice, oats, barley, and wheat) or grain products used in brewing beer which supplement the main mash ingredient.
Base grains make up the majority of the grist in all-grain beer. This group includes pale malt, Pilsner malt, Vienna malt, Munich malt, Mild ale malt, and more.