Clear Viridian vs Ink White

How close are they?

ΔE 71.2, loose: different enough that you should pick on purpose. Ink White is noticeably lighter, much more muted than Clear Viridian.

Can I use Ink White instead of Clear Viridian?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 71). Ink White is noticeably lighter, much more muted than Clear Viridian.

Can I use Clear Viridian instead of Ink White?

The same difference applies the other way round: Clear Viridian 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.