Hi eidnil, not a blond question at all.... it can be a bit confusing. Sugarpaste is also called Fondant, are you familiar with it? You can find a great home-made recipe in this site, Marshmallow Fondant or MMF. It is made of Confectioners Sugar and Marshmallows, totally edible (some store bought fondants, like Wiltons don't taste good) Now, gumpaste is also based with sugar but it has "gum" in it, which is used mostly to make flowers or some decorations, it is not toxic but not edible either. It hardens really fast. The gum is what makes it get hard. If you add gum, like gum tex or gum trag, your fondant decorations will get hard too and it will change the flavor. Hope this helps and did not confuse you more!
Gumpaste is a substance sort of like fondant. You can make flowers or figures out of it. Here is a link for you.
And welcome!
http://www.wilton.com/store/site/product.cfm?id=3E30D6EB-475A-BAC0-5E5EF66C57041711&fid=3E32BC36-475A-BAC0-5F363A0047978DFF
First of all Welcome. Fondant is kind of like a frosting with the consistency of dough. You can roll it out and cover your whole cake with it or cut out shapes with cookie cutters for decoration, or you can mold it into shapes, like flowers or people and animals and such. If you add gumpaste to these they will dry faster and harder and then as nefgaby said, they really aren't edible any more.
I also wanted to tell you, as a blond, if you had joined Cake Central and then asked - "what's a cake" now that's blond. Most people here feel there is no such thing as a dumb question so ask away. 
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