ΔE 9.4, close: similar, with a visible difference side by side. IDF Blue is a little lighter, cooler than German Gray.
Usually, if you are not matching paint already on the model. Close match (ΔE 9). IDF Blue is a little lighter, cooler than German Gray.
The same difference applies the other way round: German Gray is a little darker, 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 German Gray on the colour wheel See IDF Blue on the colour wheel
All matches: German Gray equivalents · IDF Blue equivalents