ΔE 7.3, close: similar, with a visible difference side by side. Engine Gray is a little darker than Dark Grey.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Engine Gray is a little darker than Dark Grey.
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.
See Dark Grey on the colour wheel See Engine Gray on the colour wheel
All matches: Dark Grey equivalents · Engine Gray equivalents