ΔE 11.3, fair: the same colour family, but not a straight swap. Fiery Red Ink is a little darker, warmer than Blood Angels Red. They are different kinds of paint: Citadel Blood Angels Red is a one-coat contrast-style paint and Nocturna Models Fiery Red Ink is an ink, glaze or transparent 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 11). Fiery Red Ink is a little darker, warmer than Blood Angels Red. They are different kinds of paint.
The same difference applies the other way round: Blood Angels Red is a little lighter, 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 Angels Red on the colour wheel See Fiery Red Ink on the colour wheel
All matches: Blood Angels Red equivalents · Fiery Red Ink equivalents