Pestilent Flesh vs Arabic Shadow

How close are they?

ΔE 17.3, loose: different enough that you should pick on purpose. Arabic Shadow is a little darker, warmer than Pestilent Flesh.

Can I use Arabic Shadow instead of Pestilent Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Arabic Shadow is a little darker, warmer than Pestilent Flesh.

Can I use Pestilent Flesh instead of Arabic Shadow?

The same difference applies the other way round: Pestilent Flesh is a little lighter, 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.