ΔE 7.2, close: similar, with a visible difference side by side. IJN Deep Dark Green is more saturated than Lead Grey.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). IJN Deep Dark Green is more saturated than Lead Grey.
The same difference applies the other way round: Lead Grey is more muted.
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 Lead Grey on the colour wheel See IJN Deep Dark Green on the colour wheel
All matches: Lead Grey equivalents · IJN Deep Dark Green equivalents