Brownish Green vs Desert Yellow

How close are they?

ΔE 7.5, close: similar, with a visible difference side by side. Desert Yellow is a little darker, more saturated than Brownish Green.

Can I use Desert Yellow instead of Brownish Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Desert Yellow is a little darker, more saturated than Brownish Green.

Can I use Brownish Green instead of Desert Yellow?

The same difference applies the other way round: Brownish Green is a little lighter, 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.