ΔE 18.2, loose: different enough that you should pick on purpose. Phthalo Green is much more muted, cooler than Sybarite Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Phthalo Green is much more muted, cooler than Sybarite Green.
The same difference applies the other way round: Sybarite Green is much more saturated, 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 Sybarite Green on the colour wheel See Phthalo Green on the colour wheel
All matches: Sybarite Green equivalents · Phthalo Green equivalents