Is there a difference between the 2wd head and the 4wd head? If so what is it

 

Oil feed for one , come out the side by the turbo on a 4x4.
Damper also , doesn't have a mounting bracket thing on the side .
Not alot else but I'm sure others will no mire

 

combustion chambers are smaller on 4x4. SO compression will be raised if a 4x4 head is used with 2wd pistons.

Late spec 2wd and 4x4 head used a redesigned waterway on the exhaust side.

Valves, Guides, Cam(s) bearings and spacers different on 4x4.

 

also more oil ways up to the inlet cam