ΔE 12.5, fair: the same colour family, but not a straight swap. Fresh Blood is noticeably lighter, more saturated than Astorath Red. They are different kinds of paint: Citadel Astorath Red is an opaque base/layer paint and Vallejo Fresh Blood is a fluorescent or effect 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 12). Fresh Blood is noticeably lighter, more saturated than Astorath Red. They are different kinds of paint.
The same difference applies the other way round: Astorath Red is noticeably darker, more muted.
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 Astorath Red on the colour wheel See Fresh Blood on the colour wheel
All matches: Astorath Red equivalents · Fresh Blood equivalents