ΔE 7.9, close: similar, with a visible difference side by side. Lupercal Green is more saturated, cooler than Phthalo Green.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Lupercal Green is more saturated, cooler than Phthalo Green.
The same difference applies the other way round: Phthalo Green is more muted, 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 Phthalo Green on the colour wheel See Lupercal Green on the colour wheel
All matches: Phthalo Green equivalents · Lupercal Green equivalents