Dark Marine Green vs Death World Forest

How close are they?

ΔE 18.5, loose: different enough that you should pick on purpose. Death World Forest is much more muted, warmer than Dark Marine Green.

Can I use Death World Forest instead of Dark Marine Green?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Death World Forest is much more muted, warmer than Dark Marine Green.

Can I use Dark Marine Green instead of Death World Forest?

The same difference applies the other way round: Dark Marine Green is much more saturated, 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.