Dioxazine Purple vs Deep Magenta

How close are they?

ΔE 28.1, loose: different enough that you should pick on purpose. Deep Magenta is noticeably lighter, warmer than Dioxazine Purple.

Can I use Deep Magenta instead of Dioxazine Purple?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Deep Magenta is noticeably lighter, warmer than Dioxazine Purple.

Can I use Dioxazine Purple instead of Deep Magenta?

The same difference applies the other way round: Dioxazine Purple is noticeably darker, 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.