True Copper vs Deathless Metal

How close are they?

ΔE 35.3, loose: different enough that you should pick on purpose. Deathless Metal is noticeably darker, much more muted, cooler than True Copper.

Can I use Deathless Metal instead of True Copper?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 35). Deathless Metal is noticeably darker, much more muted, cooler than True Copper.

Can I use True Copper instead of Deathless Metal?

The same difference applies the other way round: True Copper is noticeably lighter, much 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.