Prussian Blue Hue vs Ink Blue

How close are they?

ΔE 7.5, close: similar, with a visible difference side by side. Ink Blue is a little darker, warmer than Prussian Blue Hue.

Can I use Ink Blue instead of Prussian Blue Hue?

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

Can I use Prussian Blue Hue instead of Ink Blue?

The same difference applies the other way round: Prussian Blue Hue 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.