Sap Green Hue vs Dark Green

How close are they?

ΔE 15.2, loose: different enough that you should pick on purpose. Dark Green is a little lighter, more muted, cooler than Sap Green Hue.

Can I use Dark Green instead of Sap Green Hue?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Dark Green is a little lighter, more muted, cooler than Sap Green Hue.

Can I use Sap Green Hue instead of Dark Green?

The same difference applies the other way round: Sap Green Hue is a little darker, more saturated, 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.