Old Gold vs Hoard Bronze

How close are they?

ΔE 7.4, close: similar, with a visible difference side by side. Hoard Bronze is a little darker, more muted than Old Gold.

Can I use Hoard Bronze instead of Old Gold?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Hoard Bronze is a little darker, more muted than Old Gold.

Can I use Old Gold instead of Hoard Bronze?

The same difference applies the other way round: Old Gold is a little lighter, more saturated.

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.