ΔE 23.9, loose: different enough that you should pick on purpose. Phthalo Blue (Green Shade) is a little lighter, much more saturated than Macragge Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 24). Phthalo Blue (Green Shade) is a little lighter, much more saturated than Macragge Blue.
The same difference applies the other way round: Macragge Blue is a little darker, much more muted.
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 Macragge Blue on the colour wheel See Phthalo Blue (Green Shade) on the colour wheel
All matches: Macragge Blue equivalents · Phthalo Blue (Green Shade) equivalents