Space Purple vs Dark Prussian Blue

How close are they?

ΔE 7.9, close: similar, with a visible difference side by side. Dark Prussian Blue is a little darker, cooler than Space Purple.

Can I use Dark Prussian Blue instead of Space Purple?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Dark Prussian Blue is a little darker, cooler than Space Purple.

Can I use Space Purple instead of Dark Prussian Blue?

The same difference applies the other way round: Space Purple is a little lighter, 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.