I just picked up my second impact kit yesterday. I like them very muchm, but as the other responces indicated i dont think there is any difference between the two kits.
Just a quick FYI, the stands are compact, and the bag that they reccomend (Impact Light Kit #3) will give about 9 inches empty space with the brackets removed. You may want to consider a smaller bag, unless like me you end up with 2 kits, plus a backdrop stand, and reflector support arm in which case the width is perfect, and i fill the extra space with a small bag on top.
Also, CHECK THAT EVERYTHING IS INCLUDED!!!! the one i bought yesterday was missing both umbrella brackets. (B&H is overnighting them to me for free.)
Other than that, I find it a great deal for 2 stands, mounts, and umbrellas.