ΔE 14.3, fair: the same colour family, but not a straight swap. Ivory White is a little darker, more muted, warmer than Pastel Yellow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Ivory White is a little darker, more muted, warmer than Pastel Yellow.
The same difference applies the other way round: Pastel Yellow is a little lighter, 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 Pastel Yellow on the colour wheel See Ivory White on the colour wheel
All matches: Pastel Yellow equivalents · Ivory White equivalents