Terrestrial Titan vs Nightshade Purple

How close are they?

ΔE 7.2, close: similar, with a visible difference side by side. Nightshade Purple is a little darker, warmer than Terrestrial Titan.

Can I use Nightshade Purple instead of Terrestrial Titan?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Nightshade Purple is a little darker, warmer than Terrestrial Titan.

Can I use Terrestrial Titan instead of Nightshade Purple?

The same difference applies the other way round: Terrestrial Titan 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.