ΔE 21.8, loose: different enough that you should pick on purpose. Doomfire Magenta is more saturated, cooler than Space Red. They are different kinds of paint: AK Interactive Space Red is an opaque base/layer paint and Citadel Doomfire Magenta is a one-coat contrast-style 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 22). Doomfire Magenta is more saturated, cooler than Space Red. They are different kinds of paint.
The same difference applies the other way round: Space Red is more muted, warmer.
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 Space Red on the colour wheel See Doomfire Magenta on the colour wheel
All matches: Space Red equivalents · Doomfire Magenta equivalents