ΔE 21.8, loose: different enough that you should pick on purpose. Coven Purple is a little darker, much more muted, cooler than Light Plum.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Coven Purple is a little darker, much more muted, cooler than Light Plum.
The same difference applies the other way round: Light Plum is a little lighter, much 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.
See Light Plum on the colour wheel See Coven Purple on the colour wheel
All matches: Light Plum equivalents · Coven Purple equivalents