French Blue vs Russian AF Grey N.7

How close are they?

ΔE 8.1, close: similar, with a visible difference side by side. Russian AF Grey N.7 is more saturated, cooler than French Blue.

Can I use Russian AF Grey N.7 instead of French Blue?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Russian AF Grey N.7 is more saturated, cooler than French Blue.

Can I use French Blue instead of Russian AF Grey N.7?

The same difference applies the other way round: French Blue is more muted, warmer.

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.