There are several different versions of these mateials ranging from fly tying to boot and boat repair.
I have seen them demonstrated as all being so similar that they are completely interchangeable.
The maker also sells two activation lights that do the same job but where one costs several times more.
Is there a real reason for this profileration? I can’t see that is justified. 
I’m guessing the different versions are variations on a theme, maybe differing in terms of flexibility? I’ve only used the Knotsense so can’t really speak to the other products; with the lights, one is a single lamp used for curing their stuff, the other has a 3 lamp configuration, for activating photoluminescent (glow-in-the-dark) products in addition to UV curing. As to why so many different ways to skin a cat, that’s a question that can be asked to just about all the manufacturers out there - how many vises does Renzetti really need to make (I’m quite happy with my Traveller)? how many rods does Sage really need to produce, etc, etc. I guess it’s a question of what the market will bear.
Regards,
Scott
I’ve used two different kinds of Knot Sense, one has a bigger “nozzle” than the other, for applying a bigger “glob”. I bought my UV lamp somewhere else, for about $5.