Nightshade Purple vs Dark Prussian Blue

How close are they?

ΔE 8.3, close: similar, with a visible difference side by side. Dark Prussian Blue is more saturated than Nightshade Purple.

Can I use Dark Prussian Blue instead of Nightshade Purple?

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

Can I use Nightshade Purple instead of Dark Prussian Blue?

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

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.