Scarab Green vs Seraphon Blue

How close are they?

ΔE 7.6, close: similar, with a visible difference side by side. Seraphon Blue is a little darker than Scarab Green.

Can I use Seraphon Blue instead of Scarab Green?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Seraphon Blue is a little darker than Scarab Green.

Can I use Scarab Green instead of Seraphon Blue?

The same difference applies the other way round: Scarab Green is a little lighter.

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.