ΔE 15.3, loose: different enough that you should pick on purpose. Terminatus Stone is noticeably darker, more muted, cooler than Ivory White.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Terminatus Stone is noticeably darker, more muted, cooler than Ivory White.
The same difference applies the other way round: Ivory White is noticeably lighter, more saturated, 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 Terminatus Stone on the colour wheel
All matches: Ivory White equivalents · Terminatus Stone equivalents