USMC Sand FS 33711 vs Desert Tan

How close are they?

ΔE 12.6, fair: the same colour family, but not a straight swap. Desert Tan is a little darker, more muted, cooler than USMC Sand FS 33711.

Can I use Desert Tan instead of USMC Sand FS 33711?

Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Desert Tan is a little darker, more muted, cooler than USMC Sand FS 33711.

Can I use USMC Sand FS 33711 instead of Desert Tan?

The same difference applies the other way round: USMC Sand FS 33711 is a little lighter, more saturated, 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.