ΔE 27.3, loose: different enough that you should pick on purpose. Bag of Bones is noticeably darker, warmer than Skeleton Horde.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 27). Bag of Bones is noticeably darker, warmer than Skeleton Horde.
The same difference applies the other way round: Skeleton Horde is noticeably lighter, 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 Bag of Bones on the colour wheel
All matches: Skeleton Horde equivalents · Bag of Bones equivalents