ΔE 7.3, close: similar, with a visible difference side by side. Russian AF Grey N.4 is more saturated than Grey Castle.
Usually, if you are not matching paint already on the model. Close match (ΔE 7). Russian AF Grey N.4 is more saturated than Grey Castle.
The same difference applies the other way round: Grey Castle 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.
See Grey Castle on the colour wheel See Russian AF Grey N.4 on the colour wheel
All matches: Grey Castle equivalents · Russian AF Grey N.4 equivalents