ΔE 15.5, loose: different enough that you should pick on purpose. Cowling Color is much more saturated than Abaddon Black.
Can I use Cowling Color instead of Abaddon Black?
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Cowling Color is much more saturated than Abaddon Black.
Can I use Abaddon Black instead of Cowling Color?
The same difference applies the other way round: Abaddon Black is 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.