ΔE 18.9, loose: different enough that you should pick on purpose. Scarlet Red is a little darker, much more muted, cooler than Hellspawn Red.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Scarlet Red is a little darker, much more muted, cooler than Hellspawn Red.
The same difference applies the other way round: Hellspawn Red is a little lighter, much 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.
See Hellspawn Red on the colour wheel See Scarlet Red on the colour wheel
All matches: Hellspawn Red equivalents · Scarlet Red equivalents