ΔE 7.9, close: similar, with a visible difference side by side. Azure is a little lighter, cooler than Indigo Sky.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Azure is a little lighter, cooler than Indigo Sky.
The same difference applies the other way round: Indigo Sky is a little 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 Indigo Sky on the colour wheel See Azure on the colour wheel
All matches: Indigo Sky equivalents · Azure equivalents