Ushabti Bone vs Ambush Yellow

How close are they?

ΔE 19.0, loose: different enough that you should pick on purpose. Ambush Yellow is a little lighter, much more saturated than Ushabti Bone.

Can I use Ambush Yellow instead of Ushabti Bone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Ambush Yellow is a little lighter, much more saturated than Ushabti Bone.

Can I use Ushabti Bone instead of Ambush Yellow?

The same difference applies the other way round: Ushabti Bone is a little darker, much 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.