ΔE 10.1, fair: the same colour family, but not a straight swap. Phoenix Feather is a little darker, more saturated than Guilliman Flesh.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Phoenix Feather is a little darker, more saturated than Guilliman Flesh.
The same difference applies the other way round: Guilliman Flesh is a little 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 Guilliman Flesh on the colour wheel See Phoenix Feather on the colour wheel
All matches: Guilliman Flesh equivalents · Phoenix Feather equivalents