ΔE 5.6, very close: most people won’t see a difference side by side. Russian AF Grey N.3 is a little darker than Administratum Grey.
Can I use Russian AF Grey N.3 instead of Administratum Grey?
Yes, for most jobs. Very close match (ΔE 6). Russian AF Grey N.3 is a little darker than Administratum Grey.
Can I use Administratum Grey instead of Russian AF Grey N.3?
The same difference applies the other way round: Administratum 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.