ΔE 6.7, close: similar, with a visible difference side by side. Nocturnal Red is a little darker, warmer than Red Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Nocturnal Red is a little darker, warmer than Red Brown.
The same difference applies the other way round: Red Brown 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 Red Brown on the colour wheel See Nocturnal Red on the colour wheel
All matches: Red Brown equivalents · Nocturnal Red equivalents