Aren't frosting and icing the same thing?  Not at all.  That beautiful palate-pleasing layer of goodness on cakes and pastries is not always the same.

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Merriam - Webster defines frosting as, "Icing".  Well we know that's not really true.  While Dictionary.com states that frosting is, "A sweet mixture, cooked or uncooked, for coating or filling cakes, cookies and the like".  That's closure to the truth but not totally correct either.

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So let's investigate frosting first.  The frosting is generally the coating on the outside of cake.  It is usually thicker and richer than a coating of icing.  Cookbooks label frosting as more buttercream-like in texture with a more buttery taste than icing.  Frosting is a preference for cake because of its taste and ability to hold decorations like candy and rosettes.

Icing is thought to be more of a covering for pastries, sometimes cake, and tastes more sugary than frosting.  More of a glaze, thinner in consistency than it's counter-part and usually hardens more than frosting.