Ushabti Bone vs Twin Suns Yellow

How close are they?

ΔE 16.2, loose: different enough that you should pick on purpose. Twin Suns Yellow is noticeably lighter, cooler than Ushabti Bone.

Can I use Twin Suns Yellow instead of Ushabti Bone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Twin Suns Yellow is noticeably lighter, cooler than Ushabti Bone.

Can I use Ushabti Bone instead of Twin Suns Yellow?

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