ΔE 10.7, fair: the same colour family, but not a straight swap. Dark Green (IJA) is a little lighter, more muted, cooler than Vulkan Green.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Dark Green (IJA) is a little lighter, more muted, cooler than Vulkan Green.
The same difference applies the other way round: Vulkan Green is a little darker, more saturated, warmer.
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 Vulkan Green on the colour wheel See Dark Green (IJA) on the colour wheel
All matches: Vulkan Green equivalents · Dark Green (IJA) equivalents