Gehenna's Gold vs Bright Gold

How close are they?

ΔE 15.9, loose: different enough that you should pick on purpose. Bright Gold is noticeably lighter, cooler than Gehenna's Gold.

Can I use Bright Gold instead of Gehenna's Gold?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Bright Gold is noticeably lighter, cooler than Gehenna's Gold.

Can I use Gehenna's Gold instead of Bright Gold?

The same difference applies the other way round: Gehenna's Gold 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.