Cosmic Dust vs Pestilence Green

How close are they?

ΔE 16.5, loose: different enough that you should pick on purpose. Pestilence Green is a little darker, more muted, cooler than Cosmic Dust.

Can I use Pestilence Green instead of Cosmic Dust?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Pestilence Green is a little darker, more muted, cooler than Cosmic Dust.

Can I use Cosmic Dust instead of Pestilence Green?

The same difference applies the other way round: Cosmic Dust is a little lighter, more saturated, 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.