ΔE 10.9, fair: the same colour family, but not a straight swap. Ushabti Bone is a little darker, cooler than Matt Light Clay. They are different kinds of paint: AMMO by Mig Matt Light Clay is an ink, glaze or transparent paint and Citadel Ushabti Bone is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Ushabti Bone is a little darker, cooler than Matt Light Clay. They are different kinds of paint.
The same difference applies the other way round: Matt Light Clay is a little 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.
See Matt Light Clay on the colour wheel See Ushabti Bone on the colour wheel
All matches: Matt Light Clay equivalents · Ushabti Bone equivalents