ΔE 6.3, close: similar, with a visible difference side by side. USA Flat Brown is a little darker, warmer than Light Brown.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). USA Flat Brown is a little darker, warmer than Light Brown.
The same difference applies the other way round: Light Brown is a little lighter, 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 Light Brown on the colour wheel See USA Flat Brown on the colour wheel
All matches: Light Brown equivalents · USA Flat Brown equivalents