ΔE 8.6, close: similar, with a visible difference side by side. Cavalry Brown is a little lighter, more muted, warmer than Russet.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Cavalry Brown is a little lighter, more muted, warmer than Russet.
The same difference applies the other way round: Russet is a little darker, more saturated, 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 Russet on the colour wheel See Cavalry Brown on the colour wheel
All matches: Russet equivalents · Cavalry Brown equivalents