Flayed One Flesh vs Advanced Flesh Tone

How close are they?

ΔE 6.3, close: similar, with a visible difference side by side. Advanced Flesh Tone is cooler than Flayed One Flesh.

Can I use Advanced Flesh Tone instead of Flayed One Flesh?

Usually, if you are not matching paint already on the model. Close match (ΔE 6). Advanced Flesh Tone is cooler than Flayed One Flesh.

Can I use Flayed One Flesh instead of Advanced Flesh Tone?

The same difference applies the other way round: Flayed One Flesh is 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.