ΔE 11.9, fair: the same colour family, but not a straight swap. Copper (Metallic) is a little lighter than Fairy Dust.
Can I use Copper (Metallic) instead of Fairy Dust?
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Copper (Metallic) is a little lighter than Fairy Dust.
Can I use Fairy Dust instead of Copper (Metallic)?
The same difference applies the other way round: Fairy Dust is a little darker.
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.