ΔE 17.3, loose: different enough that you should pick on purpose. Ice Yellow is noticeably lighter than Ushabti Bone.
Can I use Ice Yellow instead of Ushabti Bone?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Ice Yellow is noticeably lighter than Ushabti Bone.
Can I use Ushabti Bone instead of Ice Yellow?
The same difference applies the other way round: Ushabti Bone is noticeably darker.
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.