Rachel - from Houston, TX
The major difference between gum paste and fondant is that gum paste is only used as a decorating medium. Although it is completely edible, gum paste dries very hard and is generally not eaten. For example, gum paste is wonderful for making beautiful flowers, figurines, and other decorations that would be removed from a cake before serving, but it would not be used as an icing to cover a cake because it would harden and be impossible to cut.
Fondant can also be used to make decorations, including flowers and figurines, but it does not dry as hard as gum paste. This makes it ideal for using as a rolled icing for cakes.
Fondant can be flavored by using flavored extract like vanilla, lemon, etc. I do not suggest flavoring gum paste, as it is rarely ever eaten, but also because adding flavorings or moisture to it will affect its ability to harden completely.