ΔE 6.7, close: similar, with a visible difference side by side. Sons of Horus Green is a little darker, cooler than Poison Ivy.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Sons of Horus Green is a little darker, cooler than Poison Ivy.
The same difference applies the other way round: Poison Ivy is a little lighter, 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 Poison Ivy on the colour wheel See Sons of Horus Green on the colour wheel
All matches: Poison Ivy equivalents · Sons of Horus Green equivalents