Radiant Yellow vs Daemonic Yellow

How close are they?

ΔE 15.3, loose: different enough that you should pick on purpose. Daemonic Yellow is a little darker, more saturated, warmer than Radiant Yellow.

Can I use Daemonic Yellow instead of Radiant Yellow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Daemonic Yellow is a little darker, more saturated, warmer than Radiant Yellow.

Can I use Radiant Yellow instead of Daemonic Yellow?

The same difference applies the other way round: Radiant Yellow is a little lighter, 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.