ΔE 9.7, close: similar, with a visible difference side by side. Lavender Grey is a little lighter than Dark Concrete.
Usually, if you are not matching paint already on the model. Close match (ΔE 10). Lavender Grey is a little lighter than Dark Concrete.
The same difference applies the other way round: Dark Concrete is a little darker.
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 Concrete on the colour wheel See Lavender Grey on the colour wheel
All matches: Dark Concrete equivalents · Lavender Grey equivalents