ΔE 7.4, close: similar, with a visible difference side by side. Grey Blue is a little lighter, warmer than Steel Shadow.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Grey Blue is a little lighter, warmer than Steel Shadow.
The same difference applies the other way round: Steel Shadow is a little darker, 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 Steel Shadow on the colour wheel See Grey Blue on the colour wheel
All matches: Steel Shadow equivalents · Grey Blue equivalents