Lemon Yellow vs Dorn Yellow

How close are they?

ΔE 22.2, loose: different enough that you should pick on purpose. Dorn Yellow is noticeably darker, much more saturated, warmer than Lemon Yellow.

Can I use Dorn Yellow instead of Lemon Yellow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Dorn Yellow is noticeably darker, much more saturated, warmer than Lemon Yellow.

Can I use Lemon Yellow instead of Dorn Yellow?

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