ΔE 8.6, close: similar, with a visible difference side by side. Field Blue is more muted than Gray Green (Luftwaffe).
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Field Blue is more muted than Gray Green (Luftwaffe).
The same difference applies the other way round: Gray Green (Luftwaffe) is more saturated.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Gray Green (Luftwaffe) on the colour wheel See Field Blue on the colour wheel
All matches: Gray Green (Luftwaffe) equivalents · Field Blue equivalents