ΔE 11.1, fair: the same colour family, but not a straight swap. Phthalo Green (Yellow Shade) is a little darker, more muted, cooler than Ork Flesh. They are different kinds of paint: Citadel Ork Flesh is a one-coat contrast-style paint and Golden Phthalo Green (Yellow Shade) is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Phthalo Green (Yellow Shade) is a little darker, more muted, cooler than Ork Flesh. They are different kinds of paint.
The same difference applies the other way round: Ork Flesh is a little lighter, 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 Ork Flesh on the colour wheel See Phthalo Green (Yellow Shade) on the colour wheel
All matches: Ork Flesh equivalents · Phthalo Green (Yellow Shade) equivalents