It's been awhile since I picked up the anti walk pins. But I'm pretty sure the gen2 just have a wider, stronger connecting bar. That's the bar on the outside of the receiver.
A lot of folks will argue that the A.W. pins are unnecessary, and that's probably true. I've always thought that they sure as heck can't hurt, since this type can't rotate either. But for me, these things are great, since the connecting bar gives your trigger finger a nice resting place. There's nice positive trigger finger feedback, when it's resting on that bar. Feels very natural, almost like that was its true purpose.
And I'm telling you all that, to tell you this. I prefer the thinner type, the gen1. I'm sure the other one works well also, but I was able to try the fatter one, and I didn't like it as well. And IMHO, the fatter bar solves a non existent problem. At least it's that way for the15-22. YMMV