ΔE 6.5, close: similar, with a visible difference side by side. USN Light Ghost Grey is a little darker than Dark Sea Gray.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). USN Light Ghost Grey is a little darker than Dark Sea Gray.
The same difference applies the other way round: Dark Sea Gray 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 Sea Gray on the colour wheel See USN Light Ghost Grey on the colour wheel
All matches: Dark Sea Gray equivalents · USN Light Ghost Grey equivalents