Russian Sand 7K vs Desert Yellow

How close are they?

ΔE 8.4, close: similar, with a visible difference side by side. Desert Yellow is a little lighter, cooler than Russian Sand 7K.

Can I use Desert Yellow instead of Russian Sand 7K?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Desert Yellow is a little lighter, cooler than Russian Sand 7K.

Can I use Russian Sand 7K instead of Desert Yellow?

The same difference applies the other way round: Russian Sand 7K is a little darker, warmer.

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.