ΔE 7.5, close: similar, with a visible difference side by side. IJN Black Green is more muted, warmer than Medium Russian Green S-34092.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). IJN Black Green is more muted, warmer than Medium Russian Green S-34092.
The same difference applies the other way round: Medium Russian Green S-34092 is more saturated, 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 Medium Russian Green S-34092 on the colour wheel See IJN Black Green on the colour wheel
All matches: Medium Russian Green S-34092 equivalents · IJN Black Green equivalents