Yea, easy to say, so get me a copy of the source code of both and I can check for myself.
Otherwise, from what can be observed they are very similar versions of the same engine, the only major difference is the removal of the modding/online play.
I think this is part of FU's plan, to lower the bar. He somehow got domination power and made PoR, NWN and ToEE piss poor games, and then helped with lionheart and IWD2.
Now whatever he puts out won't look worse!
It's over dude, I am not reinstalling BG2 just to try a mod. Bio had the chance to do whatever is in the mod anyway, and they chose to screw the thief PC's.