Pale Yellow vs Dead Flesh

How close are they?

ΔE 15.3, loose: different enough that you should pick on purpose. Dead Flesh is noticeably darker, more saturated than Pale Yellow.

Can I use Dead Flesh instead of Pale Yellow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Dead Flesh is noticeably darker, more saturated than Pale Yellow.

Can I use Pale Yellow instead of Dead Flesh?

The same difference applies the other way round: Pale Yellow is noticeably lighter, more muted.

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.