ΔE 12.9, fair: the same colour family, but not a straight swap. Bone White is much more muted, warmer than Skeleton Horde. They are different kinds of paint: Citadel Skeleton Horde is a one-coat contrast-style paint and Vallejo Bone White is an opaque base/layer paint, so they won’t behave the same on the model even where the colour is close.
✓ Herrick Games paint comparison chart lists these two as equivalents.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Bone White is much more muted, warmer than Skeleton Horde. They are different kinds of paint.
The same difference applies the other way round: Skeleton Horde is much more saturated, cooler.
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 Skeleton Horde on the colour wheel See Bone White on the colour wheel
All matches: Skeleton Horde equivalents · Bone White equivalents