Pallid Bone vs Human Flesh

How close are they?

ΔE 22.9, loose: different enough that you should pick on purpose. Human Flesh is noticeably darker, more muted, warmer than Pallid Bone.

Can I use Human Flesh instead of Pallid Bone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Human Flesh is noticeably darker, more muted, warmer than Pallid Bone.

Can I use Pallid Bone instead of Human Flesh?

The same difference applies the other way round: Pallid Bone is noticeably lighter, more saturated, cooler.

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.