ΔE 10.6, fair: the same colour family, but not a straight swap. Screaming Skull is a little darker, cooler than Ivory White.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Screaming Skull is a little darker, cooler than Ivory White.
The same difference applies the other way round: Ivory White is a little lighter, 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 Ivory White on the colour wheel See Screaming Skull on the colour wheel
All matches: Ivory White equivalents · Screaming Skull equivalents