ΔE 14.3, fair: the same colour family, but not a straight swap. Red Purple is a little lighter, more saturated than Carroburg Crimson. They are different kinds of paint: Citadel Carroburg Crimson is a wash/shade and Nocturna Models Red Purple 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 14). Red Purple is a little lighter, more saturated than Carroburg Crimson. They are different kinds of paint.
The same difference applies the other way round: Carroburg Crimson is a little 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 Carroburg Crimson on the colour wheel See Red Purple on the colour wheel
All matches: Carroburg Crimson equivalents · Red Purple equivalents