ΔE 5.0, very close: most people won’t see a difference side by side. Stormcover Grey is more muted than Mechanicus Standard Grey.
Can I use Stormcover Grey instead of Mechanicus Standard Grey?
Yes, for most jobs. Very close match (ΔE 5). Stormcover Grey is more muted than Mechanicus Standard Grey.
Can I use Mechanicus Standard Grey instead of Stormcover Grey?
The same difference applies the other way round: Mechanicus Standard 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.