Pale Yellow vs Screaming Skull

How close are they?

ΔE 23.0, loose: different enough that you should pick on purpose. Screaming Skull is noticeably darker, much more muted than Pale Yellow.

Can I use Screaming Skull instead of Pale Yellow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Screaming Skull is noticeably darker, much more muted than Pale Yellow.

Can I use Pale Yellow instead of Screaming Skull?

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

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.