Metallic Gold vs Bright Bronze

How close are they?

ΔE 16.8, loose: different enough that you should pick on purpose. Bright Bronze is a little darker, more muted, warmer than Metallic Gold.

Can I use Bright Bronze instead of Metallic Gold?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Bright Bronze is a little darker, more muted, warmer than Metallic Gold.

Can I use Metallic Gold instead of Bright Bronze?

The same difference applies the other way round: Metallic Gold 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.