RAF Camouflage Beige (Hemp) BS381C/389 vs Desert Tan

How close are they?

ΔE 6.1, close: similar, with a visible difference side by side. Desert Tan is more saturated than RAF Camouflage Beige (Hemp) BS381C/389.

Can I use Desert Tan instead of RAF Camouflage Beige (Hemp) BS381C/389?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Desert Tan is more saturated than RAF Camouflage Beige (Hemp) BS381C/389.

Can I use RAF Camouflage Beige (Hemp) BS381C/389 instead of Desert Tan?

The same difference applies the other way round: RAF Camouflage Beige (Hemp) BS381C/389 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.