Dark Boot Brown vs Dark Green Brown

How close are they?

ΔE 6.2, close: similar, with a visible difference side by side. Dark Green Brown is more saturated than Dark Boot Brown.

Can I use Dark Green Brown instead of Dark Boot Brown?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Dark Green Brown is more saturated than Dark Boot Brown.

Can I use Dark Boot Brown instead of Dark Green Brown?

The same difference applies the other way round: Dark Boot Brown is more muted.

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.