ΔE 10.0, fair: the same colour family, but not a straight swap. Plate Armour is a little lighter than Leadbelcher.
Can I use Plate Armour instead of Leadbelcher?
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Plate Armour is a little lighter than Leadbelcher.
Can I use Leadbelcher instead of Plate Armour?
The same difference applies the other way round: Leadbelcher is a little darker.
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.