ΔE 6.0, close: similar, with a visible difference side by side. USAF Brown is a little lighter, warmer than Brown FS30219.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). USAF Brown is a little lighter, warmer than Brown FS30219.
The same difference applies the other way round: Brown FS30219 is a little darker, 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 Brown FS30219 on the colour wheel See USAF Brown on the colour wheel
All matches: Brown FS30219 equivalents · USAF Brown equivalents