ΔE 12.8, fair: the same colour family, but not a straight swap. Alizarin Crimson Hue is a little darker, more muted than Slaughter Red. They are different kinds of paint: Army Painter Slaughter Red is a one-coat contrast-style paint and Golden Alizarin Crimson Hue is an opaque base/layer 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 13). Alizarin Crimson Hue is a little darker, more muted than Slaughter Red. They are different kinds of paint.
The same difference applies the other way round: Slaughter Red 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 Slaughter Red on the colour wheel See Alizarin Crimson Hue on the colour wheel
All matches: Slaughter Red equivalents · Alizarin Crimson Hue equivalents