ΔE 13.5, fair: the same colour family, but not a straight swap. Castellan Green is more saturated, warmer than Russian Green Uniform.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Castellan Green is more saturated, warmer than Russian Green Uniform.
The same difference applies the other way round: Russian Green Uniform 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 Russian Green Uniform on the colour wheel See Castellan Green on the colour wheel
All matches: Russian Green Uniform equivalents · Castellan Green equivalents