Granulated sugar and castor sugar are two common types of sugar. Both types of sugar contain sucrose, which is the combination of fructose and glucose. Granulated sugar and castor sugar are similar, in that, you can also get your castor sugar by grinding the granulated sugar into smaller pieces. Granulated sugar is a type of sugar that has been chemically processed into large solid crystal sugar. Castor sugar is also a type of sugar which is gotten by grinding granular sugar into smaller pieces.
The first difference between granulated sugar and castor sugar is that granulated sugar is relatively larger in size than castor sugar. Granulated sugar is like a whole solid crystal, while castor sugar looks more like powdered sugar but it is not. Granulated sugar cannot dissolve very readily in water, while castor sugar can dissolve easily in water. Granulated sugar has less moisture, while castor sugar generates more moisture due to its smaller size.