Opal Skin vs Off White

How close are they?

ΔE 16.5, loose: different enough that you should pick on purpose. Off White is a little lighter, much more muted than Opal Skin.

Can I use Off White instead of Opal Skin?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Off White is a little lighter, much more muted than Opal Skin.

Can I use Opal Skin instead of Off White?

The same difference applies the other way round: Opal Skin 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.