Terrains are based on (modified) CFS3 code, but greatly improved when compared to vintage WoFF and especially so when compared to CFS3 itself. If you mean what actual maps the WoFF terrain is based on -- I will defer to others for info. (I am assuming that various historical maps were used).
I don't recommend using the printed-out RB3D map for flying in WoFF - RB3D was a large "island" world as far as I remember, so the map will not be accurate.
If you want good maps to print out and use with the WoFF series, might I recommend the first several links located at the
following link, to excellent maps by RAF_Louvert and other WoFF map specialists. Or, if you prefer, there is also an in-flight map for use in the WoFF series. I'm sure more map specialists will pitch in with other relevant info.
Cheers and welcome to the WoFF series,
Von S