ΔE 28.3, loose: different enough that you should pick on purpose. Glorious Magenta is much more muted, cooler than Slaughter Red.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Glorious Magenta is much more muted, cooler than Slaughter Red.
The same difference applies the other way round: Slaughter Red is 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 Slaughter Red on the colour wheel See Glorious Magenta on the colour wheel
All matches: Slaughter Red equivalents · Glorious Magenta equivalents