Light Magenta vs Warlock Purple

How close are they?

ΔE 17.3, loose: different enough that you should pick on purpose. Warlock Purple is a little lighter, more saturated, warmer than Light Magenta.

Can I use Warlock Purple instead of Light Magenta?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Warlock Purple is a little lighter, more saturated, warmer than Light Magenta.

Can I use Light Magenta instead of Warlock Purple?

The same difference applies the other way round: Light Magenta is a little darker, more muted, 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.