ΔE 16.6, loose: different enough that you should pick on purpose. Arcane Gold is noticeably lighter, cooler than True Copper.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Arcane Gold is noticeably lighter, cooler than True Copper.
The same difference applies the other way round: True Copper is noticeably darker, 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.
See True Copper on the colour wheel See Arcane Gold on the colour wheel
All matches: True Copper equivalents · Arcane Gold equivalents