Sulfuric Yellow vs Desert Yellow

How close are they?

ΔE 22.4, loose: different enough that you should pick on purpose. Desert Yellow is noticeably darker, much more muted than Sulfuric Yellow.

Can I use Desert Yellow instead of Sulfuric Yellow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Desert Yellow is noticeably darker, much more muted than Sulfuric Yellow.

Can I use Sulfuric Yellow instead of Desert Yellow?

The same difference applies the other way round: Sulfuric 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.