Slaanesh Grey vs Faded Purple

How close are they?

ΔE 10.0, close: similar, with a visible difference side by side. Faded Purple is a little darker, warmer than Slaanesh Grey.

Can I use Faded Purple instead of Slaanesh Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 10). Faded Purple is a little darker, warmer than Slaanesh Grey.

Can I use Slaanesh Grey instead of Faded Purple?

The same difference applies the other way round: Slaanesh Grey 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.