A 2-in-1 blender is mainly designed for blending (shakes, smoothies, juices) and grinding (spices, small quantities of dry ingredients), using a jar and a separate grinder cup. A 3-in-1 blender adds more versatility: in addition to blending and grinding, it usually includes accessories like a chopper, whisk, and mixing cup, letting you handle extra tasks such as light chopping, whipping, or small-batch mixing without the need for a separate appliance.