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