ΔE 6.1, close: similar, with a visible difference side by side. Medium Sea Grey is a little darker than Weathered Stone.
Usually, if you are not matching paint already on the model. Close match (ΔE 6). Medium Sea Grey is a little darker than Weathered Stone.
The same difference applies the other way round: Weathered Stone 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 Weathered Stone on the colour wheel See Medium Sea Grey on the colour wheel
All matches: Weathered Stone equivalents · Medium Sea Grey equivalents