Debranding Removes The Operators Crap Stuff.
Unlocking Allows Using Any Simcard.

In Order To Debrand You'll Need
1> A Non-Branded MAIN i.e Generic
2> A FS, AnyOne Depending Upon Your Region And Languages You Want.
3> A CustomPack. See Top Sony - CDA List To Match A CustomPack With Your FS.

Once You Have All Three Files, Use This Tutorial XS++ 3.1 Guide-Flashing,Customizing,Recovering To Debrand Your Phone.

In Order To Unlock, You'll Need Your MAIN. Then Use Remove SIM-lock patch generator To Create And Apply Unlock Patch To Your Phone.