Impish Rouge vs Light Pink

How close are they?

ΔE 18.0, loose: different enough that you should pick on purpose. Light Pink is a little lighter, much more muted than Impish Rouge.

Can I use Light Pink instead of Impish Rouge?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Light Pink is a little lighter, much more muted than Impish Rouge.

Can I use Impish Rouge instead of Light Pink?

The same difference applies the other way round: Impish Rouge 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.