Desert Yellow vs Deep Khaki Drill

How close are they?

ΔE 6.6, close: similar, with a visible difference side by side. Deep Khaki Drill is a little lighter than Desert Yellow.

Can I use Deep Khaki Drill instead of Desert Yellow?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Deep Khaki Drill is a little lighter than Desert Yellow.

Can I use Desert Yellow instead of Deep Khaki Drill?

The same difference applies the other way round: Desert Yellow is a little darker.

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.