I am 16 years old and a couple days ago I made my 18 year old sisters birthday cake out of Fondant and I've heard about Gum paste but what is the difference in using it for the decorations on the cake?

Gumpaste dries harder (think those 3D flowers you see on wedding cakes). It's also generally inedible just because it doesn't taste very good. Fondant is used to cover cakes because while it's dryer than buttercream, it still stays soft.

So fondant covers the cake and can be used for some decorations, Gumpaste is used for the flowers/bows/plaques.

If I'm wanting to make a decoration for a cake that I want to roll super thin I use gumpaste instead of fondant. It can be rolled much thinner and it dries much faster.

Well welcome to CC.
Rose_N_Crantz is right . Fondant is usually yummy (can be made with marshmellows, chocolate, corn syrup etc. )

Where as Gumpaste its made with egg whites ,tylose powder and sugar (of course there are many recipes) Where is mainly use for decorations. (not to cover a cake)

But gumpaste is awsome if you want your decoration to last forever (okay maybe being sarcastic)

Hi ToxicRaindrop

I make my gumpaste by simply adding tylose or CMC to my fondant. These are just vegetable gums (or chemical equivalent in the case of CMC) and are used to make the fondant firmer and dry harder.

With CMC it's about a teaspoon of powder to a large handful of fondant and it works almost instantaneously. With the natural gums, it can take 24 hours for the fondant to firm up. The more powder you add, the harder the fondant will dry and the faster it will dry. I've never made gumpaste any other way - I think the tip was in one of Toba Garrett's books. The taste is fine - well, my children will eat it whenever they can grab a scrap, but that really doesn't mean that it tastes all that great...

Regards,
Cris.