Primary Magenta vs Warlord Purple

How close are they?

ΔE 7.3, close: similar, with a visible difference side by side. Warlord Purple is more muted than Primary Magenta.

Can I use Warlord Purple instead of Primary Magenta?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Warlord Purple is more muted than Primary Magenta.

Can I use Primary Magenta instead of Warlord Purple?

The same difference applies the other way round: Primary Magenta is 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.