ΔE 7.2, close: similar, with a visible difference side by side. USA Flat Brown is more saturated, warmer than Stormvermin Fur.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). USA Flat Brown is more saturated, warmer than Stormvermin Fur.
The same difference applies the other way round: Stormvermin Fur 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 Stormvermin Fur on the colour wheel See USA Flat Brown on the colour wheel
All matches: Stormvermin Fur equivalents · USA Flat Brown equivalents