ΔE 37.9, loose: different enough that you should pick on purpose. Seraphim Flesh is noticeably lighter, much more muted, warmer than Blood Angels Red.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 38). Seraphim Flesh is noticeably lighter, much more muted, warmer than Blood Angels Red.
The same difference applies the other way round: Blood Angels Red is noticeably darker, much more saturated, 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 Blood Angels Red on the colour wheel See Seraphim Flesh on the colour wheel
All matches: Blood Angels Red equivalents · Seraphim Flesh equivalents