ΔE 13.1, fair: the same colour family, but not a straight swap. Blue Green is noticeably lighter than Turquois (Phthalo).
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Blue Green is noticeably lighter than Turquois (Phthalo).
The same difference applies the other way round: Turquois (Phthalo) is noticeably darker.
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 Turquois (Phthalo) on the colour wheel See Blue Green on the colour wheel
All matches: Turquois (Phthalo) equivalents · Blue Green equivalents