Impish Rouge vs Pastel Pink

How close are they?

ΔE 16.1, loose: different enough that you should pick on purpose. Pastel Pink is a little lighter, more saturated, cooler than Impish Rouge.

Can I use Pastel Pink instead of Impish Rouge?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Pastel Pink is a little lighter, more saturated, cooler than Impish Rouge.

Can I use Impish Rouge instead of Pastel Pink?

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