Why don't the IE games recognize each other's saves? Or maybe they do?

[temnix]

Just what keeps Shadows of Amn with the EE engine from loading games saved in the first BGEE? The engine is the same. I mean, I haven't actually tried putting saves from the first into the folder for the second, so I don't know what would happen if I tried loading them. Maybe they wouldn't show in the menu. Or crash everything on account of missing resources. How about games saved under IWDEE and the BGEEs? What in principle prevents either of those from taking a file of IWDEE, loading its AR-whatever and the actors?