Bison-Beast vs Wrack White

How close are they?

ΔE 29.2, loose: different enough that you should pick on purpose. Wrack White is noticeably lighter, much more muted than Bison-Beast.

Can I use Wrack White instead of Bison-Beast?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 29). Wrack White is noticeably lighter, much more muted than Bison-Beast.

Can I use Bison-Beast instead of Wrack White?

The same difference applies the other way round: Bison-Beast 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.