ΔE 10.0, close: similar, with a visible difference side by side. Saddle Brown is more saturated, warmer than Grey Shadow.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Saddle Brown is more saturated, warmer than Grey Shadow.
The same difference applies the other way round: Grey Shadow is more muted, 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 Grey Shadow on the colour wheel See Saddle Brown on the colour wheel
All matches: Grey Shadow equivalents · Saddle Brown equivalents