Copper vs Brass

How close are they?

ΔE 36.0, loose: different enough that you should pick on purpose. Brass is noticeably darker, much more muted than Copper.

Can I use Brass instead of Copper?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 36). Brass is noticeably darker, much more muted than Copper.

Can I use Copper instead of Brass?

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

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.