ΔE 25.5, loose: different enough that you should pick on purpose. Dark Flesh Tone is noticeably darker, much more muted than Demon Red.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 26). Dark Flesh Tone is noticeably darker, much more muted than Demon Red.
The same difference applies the other way round: Demon Red is noticeably lighter, much more saturated.
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 Demon Red on the colour wheel See Dark Flesh Tone on the colour wheel
All matches: Demon Red equivalents · Dark Flesh Tone equivalents