They are typically used for garnishing baked goods. Crystal sugar is like coarse sugar except the crystals are pellet shaped. Confectioners 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.
Brown sugar comes in light to dark brown and has a full-bodied flavor, deep color, and soft moist texture. 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.