Blood Red Skies vs Astorath Red

How close are they?

ΔE 16.0, loose: different enough that you should pick on purpose. Astorath Red is a little darker, much more muted than Blood Red Skies.

Can I use Astorath Red instead of Blood Red Skies?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Astorath Red is a little darker, much more muted than Blood Red Skies.

Can I use Blood Red Skies instead of Astorath Red?

The same difference applies the other way round: Blood Red Skies is a little lighter, much 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.