It's just a name change. Here, we're a bit too think, I suppose, to immediatly notice the difference between the original 911 series, the 993 series, and the 996 series... So they just let us believe a Porsche is a Porsche (that's Porsh, in Americanese
).
So, no, leaving the factory, a 996 GT3RS and a _current_, water-cooled 911 GT3RS, are identical.