ΔE 18.2, loose: different enough that you should pick on purpose. Seraphim Flesh is noticeably darker, more saturated, cooler than Crusader Skin.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Seraphim Flesh is noticeably darker, more saturated, cooler than Crusader Skin.
The same difference applies the other way round: Crusader Skin is noticeably lighter, more muted, 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 Crusader Skin on the colour wheel See Seraphim Flesh on the colour wheel
All matches: Crusader Skin equivalents · Seraphim Flesh equivalents