Dark Grey vs Corvus Black

How close are they?

ΔE 6.1, close: similar, with a visible difference side by side. Corvus Black is a little darker than Dark Grey.

Can I use Corvus Black instead of Dark Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Corvus Black is a little darker than Dark Grey.

Can I use Dark Grey instead of Corvus Black?

The same difference applies the other way round: Dark Grey 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.