Brown sugar is a refined sugar that varies in color from light to dark brown and has a full-bodied flavor and soft moist texture. In the past brown sugar was semi-refined white sugar where some of the natural molasses was left in. Now brown sugar is made by adding molasses back into refined white sugar. The color will depend on the amount of molasses added during processing of the sugar. The darker the color the stronger the taste so use the one you like the best. The same weight of brown and white sugars has the same sweetness. Because white sugar is denser than brown sugar, to get equal sweetness firmly pack the brown sugar so when inverted the cup of brown sugar will hold its shape. Substituting brown sugar for white sugar in a recipe will produce a baked good that is a little moister with a slight butterscotch flavor.
Brown sugar has the tendency to lump and become hard. To avoid this, store in a glass jar or plastic bag in a cool dry place. If is becomes hard, soften it by placing a slice of apple in a plastic bag along with the brown sugar for a few days. You can also sprinkle a few drops of water on it and seal in plastic bag for a few days
Superfine (castor or caster) sugar is granulated white sugar that has superfine granules and is good for making meringues as it dissolves rapidly. You can make your own by processing granulated sugar in your food processor for a few seconds.
Crystal sugar is like coarse sugar except the crystals are pellet shaped.
Confectioners, powdered or icing sugar is granulated sugar that has been ground to a powder with cornstarch added to prevent lumping and crystallization. It comes in 4X, 6X and 10X but 10X is the one generally found in stores. 10X means that the granulated sugar has been processed ten times. Confectioners sugar is used in meringues, icings, confections, and some sweet pastry.
Granulated white sugar or table sugar has fine to medium-sized granules and is the sugar most often used in recipes. Try to find one where the crystals are not too large as they do differ from manufacturer to manufacturer. When heated granulated white sugar takes on a toffee-like color and flavor.(shared)