ΔE 14.1, fair: the same colour family, but not a straight swap. Light Phthalo Blue is noticeably lighter, cooler than Neptune Glow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Light Phthalo Blue is noticeably lighter, cooler than Neptune Glow.
The same difference applies the other way round: Neptune Glow is noticeably darker, 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 Neptune Glow on the colour wheel See Light Phthalo Blue on the colour wheel
All matches: Neptune Glow equivalents · Light Phthalo Blue equivalents