ΔE 6.6, close: similar, with a visible difference side by side. German Red Brown is cooler than Russet Shadow.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). German Red Brown is cooler than Russet Shadow.
The same difference applies the other way round: Russet Shadow is 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 Russet Shadow on the colour wheel See German Red Brown on the colour wheel
All matches: Russet Shadow equivalents · German Red Brown equivalents