Light Bronze vs Imperial Gold

How close are they?

ΔE 36.0, loose: different enough that you should pick on purpose. Imperial Gold is noticeably darker, warmer than Light Bronze.

Can I use Imperial Gold instead of Light Bronze?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 36). Imperial Gold is noticeably darker, warmer than Light Bronze.

Can I use Light Bronze instead of Imperial Gold?

The same difference applies the other way round: Light Bronze is noticeably lighter, 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.