ΔE 25.3, loose: different enough that you should pick on purpose. Screaming Skull is noticeably lighter, much more saturated than Glass Moon Light.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 25). Screaming Skull is noticeably lighter, much more saturated than Glass Moon Light.
The same difference applies the other way round: Glass Moon Light is noticeably darker, 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.
See Glass Moon Light on the colour wheel See Screaming Skull on the colour wheel
All matches: Glass Moon Light equivalents · Screaming Skull equivalents