Pale Sand vs Wraithbone

How close are they?

ΔE 16.9, loose: different enough that you should pick on purpose. Wraithbone is noticeably darker, cooler than Pale Sand.

Can I use Wraithbone instead of Pale Sand?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Wraithbone is noticeably darker, cooler than Pale Sand.

Can I use Pale Sand instead of Wraithbone?

The same difference applies the other way round: Pale Sand is noticeably lighter, 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.