ΔE 31.3, loose: different enough that you should pick on purpose. Zombie Flesh is noticeably darker, more saturated than Spectral Wolf.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Zombie Flesh is noticeably darker, more saturated than Spectral Wolf.
The same difference applies the other way round: Spectral Wolf is noticeably lighter, more muted.
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 Spectral Wolf on the colour wheel See Zombie Flesh on the colour wheel
All matches: Spectral Wolf equivalents · Zombie Flesh equivalents