ΔE 7.9, close: similar, with a visible difference side by side. Russian AF Grey N.4 is a little lighter, warmer than Kobold Grey.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). Russian AF Grey N.4 is a little lighter, warmer than Kobold Grey.
The same difference applies the other way round: Kobold Grey is a little darker, cooler.
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 Kobold Grey on the colour wheel See Russian AF Grey N.4 on the colour wheel
All matches: Kobold Grey equivalents · Russian AF Grey N.4 equivalents