Nocturne Green vs Extra Dark Seagray BS381C 640

How close are they?

ΔE 6.4, close: similar, with a visible difference side by side. Extra Dark Seagray BS381C 640 is more muted than Nocturne Green.

Can I use Extra Dark Seagray BS381C 640 instead of Nocturne Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Extra Dark Seagray BS381C 640 is more muted than Nocturne Green.

Can I use Nocturne Green instead of Extra Dark Seagray BS381C 640?

The same difference applies the other way round: Nocturne Green is more saturated.

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.