ΔE 8.3, close: similar, with a visible difference side by side. Medium Gray is more saturated than Dark Ghost Gray.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Medium Gray is more saturated than Dark Ghost Gray.
The same difference applies the other way round: Dark Ghost Gray is more muted.
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 Ghost Gray on the colour wheel See Medium Gray on the colour wheel
All matches: Dark Ghost Gray equivalents · Medium Gray equivalents