ΔE 9.1, close: similar, with a visible difference side by side. Sky Blue is a little lighter, more muted, cooler than Spirit Blue.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Sky Blue is a little lighter, more muted, cooler than Spirit Blue.
The same difference applies the other way round: Spirit Blue is a little darker, 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 Spirit Blue on the colour wheel See Sky Blue on the colour wheel
All matches: Spirit Blue equivalents · Sky Blue equivalents