ΔE 8.0, close: similar, with a visible difference side by side. A-28M Greyish Blue is a little lighter, warmer than Spectral Blue.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). A-28M Greyish Blue is a little lighter, warmer than Spectral Blue.
The same difference applies the other way round: Spectral Blue 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 Spectral Blue on the colour wheel See A-28M Greyish Blue on the colour wheel
All matches: Spectral Blue equivalents · A-28M Greyish Blue equivalents