Pastel Violet vs Mutant Hue

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Mutant Hue is a little darker, more saturated than Pastel Violet.

Can I use Mutant Hue instead of Pastel Violet?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Mutant Hue is a little darker, more saturated than Pastel Violet.

Can I use Pastel Violet instead of Mutant Hue?

The same difference applies the other way round: Pastel Violet is a little lighter, more muted.

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.