Scarlet Red vs Astorath Red

How close are they?

ΔE 8.2, close: similar, with a visible difference side by side. Astorath Red is a little darker, cooler than Scarlet Red.

Can I use Astorath Red instead of Scarlet Red?

Usually, if you are not matching paint already on the model. Close match (ΔE 8). Astorath Red is a little darker, cooler than Scarlet Red.

Can I use Scarlet Red instead of Astorath Red?

The same difference applies the other way round: Scarlet Red is a little lighter, warmer.

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.