ΔE 56.1, loose: different enough that you should pick on purpose. Radiant Orange is noticeably darker, much more muted, warmer than Iyanden Yellow.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 56). Radiant Orange is noticeably darker, much more muted, warmer than Iyanden Yellow.
The same difference applies the other way round: Iyanden Yellow is noticeably lighter, much more saturated, 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.
See Iyanden Yellow on the colour wheel See Radiant Orange on the colour wheel
All matches: Iyanden Yellow equivalents · Radiant Orange equivalents