ΔE 17.4, loose: different enough that you should pick on purpose. Ivory is noticeably darker, much more saturated than Sketching White.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Ivory is noticeably darker, much more saturated than Sketching White.
The same difference applies the other way round: Sketching White is noticeably lighter, 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 Sketching White on the colour wheel See Ivory on the colour wheel
All matches: Sketching White equivalents · Ivory equivalents