ΔE 10.7, fair: the same colour family, but not a straight swap. Ancient Copper is warmer than Bullion.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Ancient Copper is warmer than Bullion.
The same difference applies the other way round: Bullion is 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.
See Bullion on the colour wheel See Ancient Copper on the colour wheel
All matches: Bullion equivalents · Ancient Copper equivalents