Impish Rouge vs Emperor Red

How close are they?

ΔE 34.0, loose: different enough that you should pick on purpose. Emperor Red is noticeably darker, much more muted, warmer than Impish Rouge.

Can I use Emperor Red instead of Impish Rouge?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 34). Emperor Red is noticeably darker, much more muted, warmer than Impish Rouge.

Can I use Impish Rouge instead of Emperor Red?

The same difference applies the other way round: Impish Rouge is noticeably lighter, much more saturated, cooler.

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.