ΔE 10.1, fair: the same colour family, but not a straight swap. Nocturnal Red is more saturated, cooler than Brown.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Nocturnal Red is more saturated, cooler than Brown.
The same difference applies the other way round: Brown is more muted, warmer.
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 Brown on the colour wheel See Nocturnal Red on the colour wheel
All matches: Brown equivalents · Nocturnal Red equivalents