ΔE 11.6, fair: the same colour family, but not a straight swap. Phthalo Turquoise Light is more muted, warmer than Phalanx Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Phthalo Turquoise Light is more muted, warmer than Phalanx Blue.
The same difference applies the other way round: Phalanx Blue is more saturated, cooler.
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 Phalanx Blue on the colour wheel See Phthalo Turquoise Light on the colour wheel
All matches: Phalanx Blue equivalents · Phthalo Turquoise Light equivalents