ΔE 18.5, loose: different enough that you should pick on purpose. Fluorescent Pink is noticeably lighter than Doomfire Magenta. They are different kinds of paint: Citadel Doomfire Magenta is a one-coat contrast-style paint and Golden Fluorescent Pink is a fluorescent or effect 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 19). Fluorescent Pink is noticeably lighter than Doomfire Magenta. They are different kinds of paint.
The same difference applies the other way round: Doomfire Magenta is noticeably darker.
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 Doomfire Magenta on the colour wheel See Fluorescent Pink on the colour wheel
All matches: Doomfire Magenta equivalents · Fluorescent Pink equivalents