Sinai Grey vs Death World Forest

How close are they?

ΔE 16.6, loose: different enough that you should pick on purpose. Death World Forest is a little darker, cooler than Sinai Grey.

Can I use Death World Forest instead of Sinai Grey?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Death World Forest is a little darker, cooler than Sinai Grey.

Can I use Sinai Grey instead of Death World Forest?

The same difference applies the other way round: Sinai Grey is a little lighter, 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.