Yup, it's the same stuff. (edit - well, at least at it's heart it is... the stuff in the tubes is often too thin, so a lot of folks go with a thicker brand like zap a gap)
Super glues are also known as cyanoacrylates. The adhesive actually bonds the two pieces together much in the way most people think glue works.
Tenax and weld on are solvents. They essentially melt the plastic for a short period of time. The resulting bond is more of a chemical welding process than a gluing process. Testors glue in the orange tube works on the same principle.