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