is caster sugar confectioners sugar
No, caster sugar is fine-ground granulated sugar. Confectioner's sugar is a mix of ultra-fine sugar and a starch; it is sometimes called icing sugar.astor or caster sugar is the name of a very fine sugar in Britain, so named because the grains are small enough to fit though a sugar caster or sprinkler. It is sold as superfine sugar in the United States.