Note that basic difference could be in biding medium, different for metal then for fabric and the pigments could be the same. There is excellent article made by Valhlamov and Orlov about the camouflage and paints of Soviet airplanes. Note that in regards to wher the part is, there is different way to fade or to get dirt. Area over the engine is exposed from higher heat from engine and this section could change hue during time more rapidly then on the erst of airplane. maybe not to much notable on WW2 planes but this is very notable on WW1 planes.
Are you plan to do something? Kit, painting or just curiosity?
Cheers
