ΔE 6.6, close: similar, with a visible difference side by side. Black Green is a little lighter, more muted than RLM 74 Gray Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Black Green is a little lighter, more muted than RLM 74 Gray Green.
The same difference applies the other way round: RLM 74 Gray Green is a little darker, 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 RLM 74 Gray Green on the colour wheel See Black Green on the colour wheel
All matches: RLM 74 Gray Green equivalents · Black Green equivalents