ΔE 18.6, loose: different enough that you should pick on purpose. Scarlet Red is a little darker, much more muted, cooler than Carnage 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 Carnage Red.
The same difference applies the other way round: Carnage 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 Carnage Red on the colour wheel See Scarlet Red on the colour wheel
All matches: Carnage Red equivalents · Scarlet Red equivalents