Gordian Knot vs Dusken Green

How close are they?

ΔE 19.8, loose: different enough that you should pick on purpose. Dusken Green is noticeably lighter, more saturated, cooler than Gordian Knot.

Can I use Dusken Green instead of Gordian Knot?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Dusken Green is noticeably lighter, more saturated, cooler than Gordian Knot.

Can I use Gordian Knot instead of Dusken Green?

The same difference applies the other way round: Gordian Knot 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.