ΔE 11.5, fair: the same colour family, but not a straight swap. Our swatches for the two are almost the same.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). The swatches are almost the same.
The same difference applies the other way round.
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 Ironhull Grey on the colour wheel See IJN Medium Grey on the colour wheel
All matches: Ironhull Grey equivalents · IJN Medium Grey equivalents