ΔE 6.4, close: similar, with a visible difference side by side. Emerald is more saturated than Dark Green (IJA).
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Emerald is more saturated than Dark Green (IJA).
The same difference applies the other way round: Dark Green (IJA) 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 Dark Green (IJA) on the colour wheel See Emerald on the colour wheel
All matches: Dark Green (IJA) equivalents · Emerald equivalents