Khorne Red vs Perylene Violet

How close are they?

ΔE 17.2, loose: different enough that you should pick on purpose. Perylene Violet is a little lighter, much more muted than Khorne Red.

Can I use Perylene Violet instead of Khorne Red?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Perylene Violet is a little lighter, much more muted than Khorne Red.

Can I use Khorne Red instead of Perylene Violet?

The same difference applies the other way round: Khorne Red is a little darker, much more saturated.

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.