Essentially, Nosler designed the E-Tip as a lead-free Ballistic Tip, partly because they also sell a lot of bullets in Europe, where lead-free regs are more common than here. The E-Tip was developed before the Tipped TSX appeared--but they happened to both be announced at the same NRA convention show.
The cavity behind the tip is deeper in the E-Tip (or at least it was when they first appeared), and in my initial tests in various kinds of media they opened up wider, so didn't penetrate quite as deeply as standard TSX's--which were all I had then, since TTSX's weren't available until a few months later. But the difference in penetration wasn't much, at most 10%. And as noted earlier, I really can't tell any difference in on-game performance between E-Tip, TTSX's or Hornady GMX's--and have now seen plenty of animals shot with all three--so tend to pick whichever shoots well in a particular rifle.
