ΔE 11.9, fair: the same colour family, but not a straight swap. Olive Flesh is a little darker, cooler than Opal Skin.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Olive Flesh is a little darker, cooler than Opal Skin.
The same difference applies the other way round: Opal Skin is a little lighter, 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 Opal Skin on the colour wheel See Olive Flesh on the colour wheel
All matches: Opal Skin equivalents · Olive Flesh equivalents