ΔE 22.0, loose: different enough that you should pick on purpose. Crimson Hell is more muted, warmer than Dark Sky.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Crimson Hell is more muted, warmer than Dark Sky.
The same difference applies the other way round: Dark Sky is more saturated, cooler.
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 Crimson Hell on the colour wheel
All matches: Dark Sky equivalents · Crimson Hell equivalents