Abaddon Black vs Deep Rusto

How close are they?

ΔE 17.0, loose: different enough that you should pick on purpose. Deep Rusto is noticeably lighter, more saturated than Abaddon Black.

Can I use Deep Rusto instead of Abaddon Black?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Deep Rusto is noticeably lighter, more saturated than Abaddon Black.

Can I use Abaddon Black instead of Deep Rusto?

The same difference applies the other way round: Abaddon Black is noticeably darker, 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.