ΔE 3.6, very close: most people won’t see a difference side by side. Our swatches for the two are almost the same. They are different kinds of paint: Army Painter Highlord Blue is a one-coat contrast-style paint and Golden Phthalo Blue (Green Shade) is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Yes, for most jobs. Very close match (ΔE 4). The swatches are almost the same. They are different kinds of paint.
The same difference applies the other way round.
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 Highlord Blue on the colour wheel See Phthalo Blue (Green Shade) on the colour wheel
All matches: Highlord Blue equivalents · Phthalo Blue (Green Shade) equivalents