ΔE 17.7, loose: different enough that you should pick on purpose. Fire Orange is a little lighter, more muted, warmer than Blood Red. They are different kinds of paint: Army Painter Blood Red is a one-coat contrast-style paint and Reaper Fire Orange is an opaque base/layer 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). Fire Orange is a little lighter, more muted, warmer than Blood Red. They are different kinds of paint.
The same difference applies the other way round: Blood Red is a little darker, more saturated, 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.
See Blood Red on the colour wheel See Fire Orange on the colour wheel
All matches: Blood Red equivalents · Fire Orange equivalents