ΔE 8.6, close: similar, with a visible difference side by side. J.A. Green is a little darker, cooler than Mid Feldgrau.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). J.A. Green is a little darker, cooler than Mid Feldgrau.
The same difference applies the other way round: Mid Feldgrau is a little lighter, warmer.
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 Mid Feldgrau on the colour wheel See J.A. Green on the colour wheel
All matches: Mid Feldgrau equivalents · J.A. Green equivalents