ΔE 6.8, close: similar, with a visible difference side by side. Dark Green BS381C/641 is more muted than Dark Reaper.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Dark Green BS381C/641 is more muted than Dark Reaper.
The same difference applies the other way round: Dark Reaper 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 Dark Reaper on the colour wheel See Dark Green BS381C/641 on the colour wheel
All matches: Dark Reaper equivalents · Dark Green BS381C/641 equivalents