ΔE 19.2, loose: different enough that you should pick on purpose. Cayman Green is more muted, cooler than Cokum Copper.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Cayman Green is more muted, cooler than Cokum Copper.
The same difference applies the other way round: Cokum Copper is 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.
See Cokum Copper on the colour wheel See Cayman Green on the colour wheel
All matches: Cokum Copper equivalents · Cayman Green equivalents