ΔE 13.8, fair: the same colour family, but not a straight swap. Baal Red is a little darker, more muted than Red Fluor. They are different kinds of paint: AK Interactive Red Fluor is a fluorescent or effect paint and Citadel Baal Red is a one-coat contrast-style paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Baal Red is a little darker, more muted than Red Fluor. They are different kinds of paint.
The same difference applies the other way round: Red Fluor is a little lighter, more saturated.
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 Red Fluor on the colour wheel See Baal Red on the colour wheel
All matches: Red Fluor equivalents · Baal Red equivalents