Blinding Light vs Skeleton Horde

How close are they?

ΔE 32.8, loose: different enough that you should pick on purpose. Skeleton Horde is noticeably darker, much more saturated than Blinding Light.

Can I use Skeleton Horde instead of Blinding Light?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 33). Skeleton Horde is noticeably darker, much more saturated than Blinding Light.

Can I use Blinding Light instead of Skeleton Horde?

The same difference applies the other way round: Blinding Light is noticeably lighter, 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.