ΔE 7.6, close: similar, with a visible difference side by side. Corvus Black is a little darker than Schwarzgrau RLM 66.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Corvus Black is a little darker than Schwarzgrau RLM 66.
The same difference applies the other way round: Schwarzgrau RLM 66 is a little lighter.
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 Schwarzgrau RLM 66 on the colour wheel See Corvus Black on the colour wheel
All matches: Schwarzgrau RLM 66 equivalents · Corvus Black equivalents