whats the difference between them? and what are they each used for?

Gumtex is a Wilton product.

www.Wilton.com has all the info for all their products (including glucose).

The Wilton site also has projects & ideas (as well as recipes), in addition to tons of help for using all the products they sell.

In order to understand cake decorating and candy making lingo, it's helpful to know the correct terms.

Glossary of cake decorating and candy making terms:

http://www.wrenscottage.com/kitchen/glossary.php

http://fromkarenskitchen.com/tips/glossary.php

http://candy.about.com/od/candybasics/u/candybasics.htm

http://www.postandcourier.com/food/glossary/

HTH