ΔE 16.1, loose: different enough that you should pick on purpose. Abyss Blue is noticeably lighter, more muted, cooler than Dark Sky.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Abyss Blue is noticeably lighter, more muted, cooler than Dark Sky.
The same difference applies the other way round: Dark Sky is noticeably darker, more saturated, warmer.
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.
See Dark Sky on the colour wheel See Abyss Blue on the colour wheel
All matches: Dark Sky equivalents · Abyss Blue equivalents