ΔE 12.3, fair: the same colour family, but not a straight swap. Parchment is noticeably darker, more saturated than Ivory White.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Parchment is noticeably darker, more saturated than Ivory White.
The same difference applies the other way round: Ivory White is noticeably lighter, 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 Ivory White on the colour wheel See Parchment on the colour wheel
All matches: Ivory White equivalents · Parchment equivalents