Can someone tell me the differences between the 3B engine from a 200 20vt turbo and the AAN engine from an ur-S4 or ur-S6? I know that the AAN is distributorless, but aside from that, what are the differences? Thanks.

The AAN has the RS2 intake cam(milder exhaust cam, though).

There are fair amount of differences. Do you have something specific in mind?

I would assume you are thinking about a swap into an ur q. With that said, I would say the AAN has a higher Hp potential, but is much more difficult and expensive to swap into an ur q.