Howling Sand vs Skeleton Horde

How close are they?

ΔE 16.7, loose: different enough that you should pick on purpose. Skeleton Horde is a little darker, much more saturated, warmer than Howling Sand.

Can I use Skeleton Horde instead of Howling Sand?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Skeleton Horde is a little darker, much more saturated, warmer than Howling Sand.

Can I use Howling Sand instead of Skeleton Horde?

The same difference applies the other way round: Howling Sand is a little lighter, much more muted, 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.