ΔE 6.4, close: similar, with a visible difference side by side. Dark Boot Brown is a little lighter, warmer than Field Grey Base #1 (Green uniform).
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Dark Boot Brown is a little lighter, warmer than Field Grey Base #1 (Green uniform).
The same difference applies the other way round: Field Grey Base #1 (Green uniform) 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 Field Grey Base #1 (Green uniform) on the colour wheel See Dark Boot Brown on the colour wheel
All matches: Field Grey Base #1 (Green uniform) equivalents · Dark Boot Brown equivalents