It turns out, powdered sugar is made by grinding granulated sugar into a fine powder, which is then sifted to remove any lumps. This process makes powdered sugar dissolve much more easily, making it perfect for icing, glazes, and other sweet treats. But, if you try to use granulated sugar instead, you might end up with a grainy, unpleasant texture.
Now, you might be thinking, "But what about all those DIY tutorials that claim you can make your own powdered sugar at home?" Well, let me tell you, those tutorials are not entirely wrong, but they're not exactly right either. You can try blending granulated sugar in a food processor until it's finely ground, but it won't be the same as store-bought powdered sugar.