Twilight Blue vs Prussian Blue

How close are they?

ΔE 8.5, close: similar, with a visible difference side by side. Prussian Blue is more saturated, warmer than Twilight Blue.

Can I use Prussian Blue instead of Twilight Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Prussian Blue is more saturated, warmer than Twilight Blue.

Can I use Twilight Blue instead of Prussian Blue?

The same difference applies the other way round: Twilight Blue is more muted, 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.