While they both have a bold and rich chocolate flavor, chocolate frosting is typically a bit thicker and creamier than icing. It's usually thick enough to hold a point and can be piped onto cookies, cakes and cupcakes. Chocolate icing (especially this cooked chocolate icing) is a bit thinner and smoother, making it perfect for pouring on top of a sheet cake or brownies. It will harden as it cools.