ΔE 9.1, close: similar, with a visible difference side by side. Steel Grey is a little darker, cooler than Frost Blue.
✓ Two Thin Coats comparison chart lists these two as equivalents.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). Steel Grey is a little darker, cooler than Frost Blue.
The same difference applies the other way round: Frost Blue is a little lighter, 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 Frost Blue on the colour wheel See Steel Grey on the colour wheel
All matches: Frost Blue equivalents · Steel Grey equivalents