ΔE 8.6, close: similar, with a visible difference side by side. Orc Green is a little lighter, warmer than Greenskin.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Orc Green is a little lighter, warmer than Greenskin.
The same difference applies the other way round: Greenskin is a little darker, 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 Greenskin on the colour wheel See Orc Green on the colour wheel
All matches: Greenskin equivalents · Orc Green equivalents