Sacred Scarlet vs Astorath Red

How close are they?

ΔE 15.4, loose: different enough that you should pick on purpose. Astorath Red is noticeably darker, more muted, cooler than Sacred Scarlet.

Can I use Astorath Red instead of Sacred Scarlet?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Astorath Red is noticeably darker, more muted, cooler than Sacred Scarlet.

Can I use Sacred Scarlet instead of Astorath Red?

The same difference applies the other way round: Sacred Scarlet is noticeably lighter, more saturated, 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.