There are two important differences between this and other adapters. First, this is a dual adapter, with two USB ports so that you can charge both an iPhone and iPad simultaneously.
The second thing, and most importantly, is that this adapter supports the higher power charging that the iPad Air requires. Older iPads used a 10 watt 2 amp charger. The new Airs require 12 watts at 2.1 amps. Why this is important is that if an Air's battery is *completely* drained, the old adapters did not provide enough power to "kickstart" the battery to get re-charging to begin. They work okay (albeit slowly) if the battery still has a partial charge, but do not work at all if completely drained. This higher power adapter solves this problem.
It's a 17 watt charger, with 12 watts on the top port for iPads, and 5 watts on the lower port for iPhones. A great solution instead of carrying two adapters around, plus of course it's a lot cheaper than buying two adapters.