Ushabti Bone vs Desert Sand

How close are they?

ΔE 17.2, loose: different enough that you should pick on purpose. Desert Sand is noticeably lighter, more saturated than Ushabti Bone.

Can I use Desert Sand instead of Ushabti Bone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Desert Sand is noticeably lighter, more saturated than Ushabti Bone.

Can I use Ushabti Bone instead of Desert Sand?

The same difference applies the other way round: Ushabti Bone is noticeably darker, 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.