ΔE 15.4, loose: different enough that you should pick on purpose. Ivory White is more muted, warmer than Cremeweiss RAL 9001.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Ivory White is more muted, warmer than Cremeweiss RAL 9001.
The same difference applies the other way round: Cremeweiss RAL 9001 is 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 Cremeweiss RAL 9001 on the colour wheel See Ivory White on the colour wheel
All matches: Cremeweiss RAL 9001 equivalents · Ivory White equivalents