Red Copper vs Brass

How close are they?

ΔE 15.0, loose: different enough that you should pick on purpose. Brass is a little darker, more muted, warmer than Red Copper.

Can I use Brass instead of Red Copper?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Brass is a little darker, more muted, warmer than Red Copper.

Can I use Red Copper instead of Brass?

The same difference applies the other way round: Red Copper is a little lighter, 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.