ΔE 12.5, fair: the same colour family, but not a straight swap. Vambrace Brown is noticeably lighter than Sylvaneth Bark.
Can I use Vambrace Brown instead of Sylvaneth Bark?
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Vambrace Brown is noticeably lighter than Sylvaneth Bark.
Can I use Sylvaneth Bark instead of Vambrace Brown?
The same difference applies the other way round: Sylvaneth Bark is noticeably 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.