No difference there, that's engine displacement. You definitely could pull it off, but most likely you would lose your AWD, due to computer problems.\

To be honest, I'd love to do an S62 swap in my truck and make it into a true, one-of-none E53 X5M, but after seeing the amount of time it's taken to get one working in my friend's Z4, I don't think I could bring myself to do it, unless I got a motor stupid-cheap and could figure out a way to wire it right. I think the best approach would be to wire up the ITBs as a single unit and use 1 MAF, so that the factory computer could just think it's an M62. As far as VANOS, I would think an RPM window switch would work on that too.