Biggest difference is the sound. The 2 tap has 2 tungsten rattles in it chamber which creates a deeper, slower "knock", if you will. Just gives the bass something different. Last summer my buddy and I were fishing a pretty shallow flat (5 ft) and were burning Red Eyed Shads above some weeds (milfoil, coon tail). He had the 2 Tap and I had the regular Red Eyed. Both 1/2 oz. I was using bone color and he oyster, or something like that. Pretty similar colors.
In an hour stretch he caught 6 bass and I caught 1. Now, who knows if the 2 Tap made a difference, but I was sold! I ended up buying a few but plan on stocking up on a few more colors.
Here's an example of how the sounds differ.