ΔE 8.3, close: similar, with a visible difference side by side. Extra Dark Green is more saturated than Hardened Carapace.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Extra Dark Green is more saturated than Hardened Carapace.
The same difference applies the other way round: Hardened Carapace 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 Hardened Carapace on the colour wheel See Extra Dark Green on the colour wheel
All matches: Hardened Carapace equivalents · Extra Dark Green equivalents