Verdigris vs Bright Green Blue

How close are they?

ΔE 20.5, loose: different enough that you should pick on purpose. Bright Green Blue is a little lighter, much more muted than Verdigris.

Can I use Bright Green Blue instead of Verdigris?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 20). Bright Green Blue is a little lighter, much more muted than Verdigris.

Can I use Verdigris instead of Bright Green Blue?

The same difference applies the other way round: Verdigris is a little 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.