Desert Sand vs Senshi Skin

How close are they?

ΔE 6.6, close: similar, with a visible difference side by side. Senshi Skin is a little lighter, more muted than Desert Sand.

Can I use Senshi Skin instead of Desert Sand?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Senshi Skin is a little lighter, more muted than Desert Sand.

Can I use Desert Sand instead of Senshi Skin?

The same difference applies the other way round: Desert Sand is a little darker, more saturated.

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.