ΔE 8.1, close: similar, with a visible difference side by side. Merm Green is more saturated, warmer than Mid Feldgrau.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Merm Green is more saturated, warmer than Mid Feldgrau.
The same difference applies the other way round: Mid Feldgrau is more muted, cooler.
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 Merm Green on the colour wheel
All matches: Mid Feldgrau equivalents · Merm Green equivalents