ΔE 20.3, loose: different enough that you should pick on purpose. Flesh Tearers Red is noticeably lighter, much more saturated, warmer than Slaughter Red.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Flesh Tearers Red is noticeably lighter, much more saturated, warmer than Slaughter Red.
The same difference applies the other way round: Slaughter Red is noticeably darker, much more muted, cooler.
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 Slaughter Red on the colour wheel See Flesh Tearers Red on the colour wheel
All matches: Slaughter Red equivalents · Flesh Tearers Red equivalents