Ushabti Bone vs Pale Yellow

How close are they?

ΔE 16.8, loose: different enough that you should pick on purpose. Pale Yellow is noticeably lighter, more saturated than Ushabti Bone.

Can I use Pale Yellow instead of Ushabti Bone?

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

Can I use Ushabti Bone instead of Pale Yellow?

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.