ΔE 13.2, fair: the same colour family, but not a straight swap. Guilliman Flesh is noticeably darker, more muted than Pastel Salmon.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Guilliman Flesh is noticeably darker, more muted than Pastel Salmon.
The same difference applies the other way round: Pastel Salmon is noticeably lighter, 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 Pastel Salmon on the colour wheel See Guilliman Flesh on the colour wheel
All matches: Pastel Salmon equivalents · Guilliman Flesh equivalents