Desert Yellow vs Washable Dust

How close are they?

ΔE 6.3, close: similar, with a visible difference side by side. Washable Dust is a little darker than Desert Yellow.

Can I use Washable Dust instead of Desert Yellow?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Washable Dust is a little darker than Desert Yellow.

Can I use Desert Yellow instead of Washable Dust?

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

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.