Eidolon Purple Clear vs Plum

How close are they?

ΔE 20.1, loose: different enough that you should pick on purpose. Plum is a little lighter, much more muted, warmer than Eidolon Purple Clear.

Can I use Plum instead of Eidolon Purple Clear?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Plum is a little lighter, much more muted, warmer than Eidolon Purple Clear.

Can I use Eidolon Purple Clear instead of Plum?

The same difference applies the other way round: Eidolon Purple Clear is a little darker, much more saturated, 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.