Dreadful Visage vs Human Flesh

How close are they?

ΔE 20.0, loose: different enough that you should pick on purpose. Human Flesh is a little lighter, much more saturated, warmer than Dreadful Visage.

Can I use Human Flesh instead of Dreadful Visage?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Human Flesh is a little lighter, much more saturated, warmer than Dreadful Visage.

Can I use Dreadful Visage instead of Human Flesh?

The same difference applies the other way round: Dreadful Visage is a little darker, much more muted, 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.