Hull Red vs Abaddon Black

How close are they?

ΔE 17.6, loose: different enough that you should pick on purpose. Abaddon Black is a little darker, much more muted than Hull Red.

Can I use Abaddon Black instead of Hull Red?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Abaddon Black is a little darker, much more muted than Hull Red.

Can I use Hull Red instead of Abaddon Black?

The same difference applies the other way round: Hull Red is a little lighter, much more saturated.

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.