ΔE 29.1, loose: different enough that you should pick on purpose. Magenta is a little lighter, much more saturated than Crimson Hell.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 29). Magenta is a little lighter, much more saturated than Crimson Hell.
The same difference applies the other way round: Crimson Hell 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 Crimson Hell on the colour wheel See Magenta on the colour wheel
All matches: Crimson Hell equivalents · Magenta equivalents