ΔE 7.9, close: similar, with a visible difference side by side. Sky Grey is a little darker than Longbeard Grey.
✓ Herrick Games paint comparison chart lists these two as equivalents.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Sky Grey is a little darker than Longbeard Grey.
The same difference applies the other way round: Longbeard 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 Longbeard Grey on the colour wheel See Sky Grey on the colour wheel
All matches: Longbeard Grey equivalents · Sky Grey equivalents