Burnt Iron vs Leadbelcher

How close are they?

ΔE 27.9, loose: different enough that you should pick on purpose. Leadbelcher is noticeably lighter, much more muted than Burnt Iron.

Can I use Leadbelcher instead of Burnt Iron?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 28). Leadbelcher is noticeably lighter, much more muted than Burnt Iron.

Can I use Burnt Iron instead of Leadbelcher?

The same difference applies the other way round: Burnt Iron is noticeably darker, much 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.