Antique Gold vs Ancient Copper

How close are they?

ΔE 18.5, loose: different enough that you should pick on purpose. Ancient Copper is noticeably lighter, more saturated, warmer than Antique Gold.

Can I use Ancient Copper instead of Antique Gold?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Ancient Copper is noticeably lighter, more saturated, warmer than Antique Gold.

Can I use Antique Gold instead of Ancient Copper?

The same difference applies the other way round: Antique Gold is noticeably darker, more muted, 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.