ΔE 17.1, loose: different enough that you should pick on purpose. Sunny Yellow is noticeably lighter, cooler than Dorn Yellow.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Sunny Yellow is noticeably lighter, cooler than Dorn Yellow.
The same difference applies the other way round: Dorn Yellow is noticeably darker, warmer.
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 Dorn Yellow on the colour wheel See Sunny Yellow on the colour wheel
All matches: Dorn Yellow equivalents · Sunny Yellow equivalents