Fulgurite Copper vs Orgoth Bronze

How close are they?

ΔE 37.3, loose: different enough that you should pick on purpose. Orgoth Bronze is noticeably darker, much more muted, cooler than Fulgurite Copper.

Can I use Orgoth Bronze instead of Fulgurite Copper?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 37). Orgoth Bronze is noticeably darker, much more muted, cooler than Fulgurite Copper.

Can I use Fulgurite Copper instead of Orgoth Bronze?

The same difference applies the other way round: Fulgurite Copper is noticeably lighter, much more saturated, 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.