ΔE 13.3, fair: the same colour family, but not a straight swap. Fiery Red Ink is a little darker, more saturated, warmer than Spiritstone Red. They are different kinds of paint: Citadel Spiritstone Red is a technical paint or medium 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 13). Fiery Red Ink is a little darker, more saturated, warmer than Spiritstone Red. They are different kinds of paint.
The same difference applies the other way round: Spiritstone Red is a little lighter, more muted, 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 Spiritstone Red on the colour wheel See Fiery Red Ink on the colour wheel
All matches: Spiritstone Red equivalents · Fiery Red Ink equivalents