ΔE 18.1, loose: different enough that you should pick on purpose. Medium Magenta is a little lighter, much more saturated than Moody Mauve. They are different kinds of paint: Army Painter Moody Mauve is a one-coat contrast-style paint and Golden Medium Magenta is an ink, glaze or transparent paint, so they won’t behave the same on the model even where the colour is close.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Medium Magenta is a little lighter, much more saturated than Moody Mauve. They are different kinds of paint.
The same difference applies the other way round: Moody Mauve is a little darker, much more muted.
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 Moody Mauve on the colour wheel See Medium Magenta on the colour wheel
All matches: Moody Mauve equivalents · Medium Magenta equivalents