Eldritch vs Jade Green

How close are they?

ΔE 20.6, loose: different enough that you should pick on purpose. Jade Green is noticeably lighter, more saturated, cooler than Eldritch.

Can I use Jade Green instead of Eldritch?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Jade Green is noticeably lighter, more saturated, cooler than Eldritch.

Can I use Eldritch instead of Jade Green?

The same difference applies the other way round: Eldritch is noticeably darker, more muted, 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.