Charming Chartreuse vs Sulfur Yellow

How close are they?

ΔE 23.3, loose: different enough that you should pick on purpose. Sulfur Yellow is more saturated, warmer than Charming Chartreuse.

Can I use Sulfur Yellow instead of Charming Chartreuse?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Sulfur Yellow is more saturated, warmer than Charming Chartreuse.

Can I use Charming Chartreuse instead of Sulfur Yellow?

The same difference applies the other way round: Charming Chartreuse is 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.