Pearl sugar consists of large opaque white grains that look much like the large-grain salt you often see on pretzels in malls and ballparks. This variety of sugar withstands high heat without melting, so it makes a wonderful garnish for sprinkling on cookies, muffins, and scones before baking.
Sanding sugar’s extra-large crystals also will not melt in the oven, but sanding sugar is clear and sparkly unlike the opaque pearl sugar. Sanding sugar is also available in many colors.
Both varieties can be found in specialty grocery stores, the cake-decorating section of many crafts stores, and at online sources, such as kingarthurflour.com.