Star Blue vs Shadow Thorn

How close are they?

ΔE 7.7, close: similar, with a visible difference side by side. Shadow Thorn is a little darker, warmer than Star Blue.

Can I use Shadow Thorn instead of Star Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Shadow Thorn is a little darker, warmer than Star Blue.

Can I use Star Blue instead of Shadow Thorn?

The same difference applies the other way round: Star Blue is a little lighter, cooler.

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.