WWI German Mauve vs Warpfiend Grey

How close are they?

ΔE 7.7, close: similar, with a visible difference side by side. Warpfiend Grey is cooler than WWI German Mauve.

Can I use Warpfiend Grey instead of WWI German Mauve?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Warpfiend Grey is cooler than WWI German Mauve.

Can I use WWI German Mauve instead of Warpfiend Grey?

The same difference applies the other way round: WWI German Mauve is 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.