Wraithbone vs Bright Pale Green

How close are they?

ΔE 17.1, loose: different enough that you should pick on purpose. Bright Pale Green is a little lighter, more saturated, cooler than Wraithbone.

Can I use Bright Pale Green instead of Wraithbone?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Bright Pale Green is a little lighter, more saturated, cooler than Wraithbone.

Can I use Wraithbone instead of Bright Pale Green?

The same difference applies the other way round: Wraithbone is a little darker, more muted, 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.