ΔE 19.2, loose: different enough that you should pick on purpose. Blue Green is a little darker, more muted, cooler than Light Turquois (Phthalo).
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Blue Green is a little darker, more muted, cooler than Light Turquois (Phthalo).
The same difference applies the other way round: Light Turquois (Phthalo) 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 Light Turquois (Phthalo) on the colour wheel See Blue Green on the colour wheel
All matches: Light Turquois (Phthalo) equivalents · Blue Green equivalents