RAF Sky Grey vs Administratum Grey

How close are they?

ΔE 8.2, close: similar, with a visible difference side by side. Administratum Grey is a little darker than RAF Sky Grey.

Can I use Administratum Grey instead of RAF Sky Grey?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Administratum Grey is a little darker than RAF Sky Grey.

Can I use RAF Sky Grey instead of Administratum Grey?

The same difference applies the other way round: RAF Sky 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.