The 2nd and 3rd are the same. The only difference is is that they are showing you on that pregen character what it goes to if/when he levels. They just did the math for you already like they do with all their pregens.
They only put the stuff in the back of the MM to allow people who cant wait to play one of those races. And like all monsters and races in the MM they dont follow the same rules as player characters do.
So you basically have the benefit of them putting out the fleshed out Warforged rules for you early.
I would have rather seen Gnomes or (Heaven Forbid) Drow get fleshed out now since FR is the 1st realm to be released. They could have waited to release the Warforged until next year around the time the Eberron books come out. But thats just my preference.