ΔE 9.2, close: similar, with a visible difference side by side. Neutral Grey is a little lighter, more muted than Bright Brown Grey.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Neutral Grey is a little lighter, more muted than Bright Brown Grey.
The same difference applies the other way round: Bright Brown Grey is a little darker, more saturated.
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 Bright Brown Grey on the colour wheel See Neutral Grey on the colour wheel
All matches: Bright Brown Grey equivalents · Neutral Grey equivalents