ΔE 8.1, close: similar, with a visible difference side by side. Longbeard Grey is more muted than Medium Grey.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Longbeard Grey is more muted than Medium Grey.
The same difference applies the other way round: Medium Grey is more saturated.
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 Medium Grey on the colour wheel See Longbeard Grey on the colour wheel
All matches: Medium Grey equivalents · Longbeard Grey equivalents