Cultist Purple vs Ghost Blue

How close are they?

ΔE 7.5, close: similar, with a visible difference side by side. Ghost Blue is more saturated, cooler than Cultist Purple.

Can I use Ghost Blue instead of Cultist Purple?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Ghost Blue is more saturated, cooler than Cultist Purple.

Can I use Cultist Purple instead of Ghost Blue?

The same difference applies the other way round: Cultist Purple is more muted, 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.