ΔE 10.8, fair: the same colour family, but not a straight swap. White Blue is a little lighter, more saturated than Ulthuan Grey.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). White Blue is a little lighter, more saturated than Ulthuan Grey.
The same difference applies the other way round: Ulthuan Grey is a little darker, 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 Ulthuan Grey on the colour wheel See White Blue on the colour wheel
All matches: Ulthuan Grey equivalents · White Blue equivalents