Dark Sea Gray vs Russ. AF Grey N.8

How close are they?

ΔE 7.5, close: similar, with a visible difference side by side. Russ. AF Grey N.8 is more saturated than Dark Sea Gray.

Can I use Russ. AF Grey N.8 instead of Dark Sea Gray?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Russ. AF Grey N.8 is more saturated than Dark Sea Gray.

Can I use Dark Sea Gray instead of Russ. AF Grey N.8?

The same difference applies the other way round: Dark Sea Gray 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.