• Caster sugar is finer than granulated sugar.sugar image by Aleksandr Ugorenkov from Fotolia.com
  
  The term "sugar" refers to many more products than the common granulated version. Fruit sugar, for example, consists of slightly smaller particles than granulated sugar and is included in many sweetened powdered mixes. Sanding sugar, on the other hand, has much larger particles than granulated sugar and is often sprinkled onto desserts as a finishing touch. Caster (or castor) sugar, known as superfine sugar in the U.S., differs from granulated sugar in several important ways.
  
  

Size

• Caster sugar particles are significantly smaller than those of granulated sugar. If you examine granulated sugar closely, you should be able to see each particle without too much difficulty. Caster sugar, on the other hand, looks like a powder; the individual particles are not clearly visible to the naked eye under most circumstances.
  
  

Dissolvability

• Thanks to the small size of its particles, caster sugar dissolves more easily in liquid than normal granulated sugar. You should be able to dissolve caster liquid in water almost immediately. On the other hand, it may take several minutes of constant, brisk mixing to dissolve granulated sugar in water.
  
  

Uses

• You can use granulated sugar in most recipes where the texture of the sugar is relatively unimportant. These include jams and jellies, cakes, pies and most other common, familiar items. You can use caster sugar in these items as well as dishes that require a finer sugar. These dishes include meringues and cold liquids. You can also use caster sugar in place of the even finer powdered sugar as a powdery topping for desserts.