Non-stick, as the name suggests, prevents any of the food material that you place in the device from sticking to the sides of the sandwich maker. Cooking any dough based substance in a normal vessel will result in the food getting stuck to the walls of the said vessel and it will make the cleaning process entirely difficult. Given the ingredients of a sandwich, it is better to use nonstick coated maker since it is easy to clean and also it prevents the food from sticking to the surface.