Naggaroth Night vs Nightmare Purple

How close are they?

ΔE 8.6, close: similar, with a visible difference side by side. Nightmare Purple is more saturated, warmer than Naggaroth Night.

Can I use Nightmare Purple instead of Naggaroth Night?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Nightmare Purple is more saturated, warmer than Naggaroth Night.

Can I use Naggaroth Night instead of Nightmare Purple?

The same difference applies the other way round: Naggaroth Night 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.