Spoke with a buddy of mine who recently did a SO interview and the primary difference between the DEFO/SO was the SIM profile. HR/Technical interviews were similar with the SO interview perhaps being slightly more Tech oriented (always depends on the interview team).
The internet gouge provides a good background onto the type of technical questions CX likes to ask. Handling the Big Jets also seems to be the CX Bible so if you can get your hands on a copy it couldn't hurt.