Well, in a way they are the same thing because they produce similar results. The recipes are a bit different when using one versus the other.
They are made of different bases but both will produce hardening results. Tylose is an alternative product to use in making gumpaste instead of gum tragacanth. Some folks find it is less expensive,, easier to work with, that it holds up better in areas of higher humidity and it is whiter in color.
Wilton's Gum-Tex is actually made with gum karaya, a cheaper alternative to gum tragacanth which was traditionally used for making gumpaste.
Some folks find that using Tylose makes a better tasting and smelling gumpaste. Gum-Tex does have a bit of a strong vinegar smell to it.