ΔE 14.4, fair: the same colour family, but not a straight swap. Phthalo Green (Yellow Shade) is a little lighter, more saturated, cooler than Biel-Tan Green. They are different kinds of paint: Citadel Biel-Tan Green is a wash/shade and Golden Phthalo Green (Yellow Shade) is an opaque base/layer 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 14). Phthalo Green (Yellow Shade) is a little lighter, more saturated, cooler than Biel-Tan Green. They are different kinds of paint.
The same difference applies the other way round: Biel-Tan Green is a little darker, 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 Biel-Tan Green on the colour wheel See Phthalo Green (Yellow Shade) on the colour wheel
All matches: Biel-Tan Green equivalents · Phthalo Green (Yellow Shade) equivalents