ΔE 4.4, very close: most people won’t see a difference side by side. Mechanicus Standard Grey is more saturated than Bleached Strap Grey.
Can I use Mechanicus Standard Grey instead of Bleached Strap Grey?
Yes, for most jobs. Very close match (ΔE 4). Mechanicus Standard Grey is more saturated than Bleached Strap Grey.
Can I use Bleached Strap Grey instead of Mechanicus Standard Grey?
The same difference applies the other way round: Bleached Strap Grey is more muted.
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.