Purple Rain vs Andrea Blue

How close are they?

ΔE 22.5, loose: different enough that you should pick on purpose. Andrea Blue is a little lighter, more muted, cooler than Purple Rain.

Can I use Andrea Blue instead of Purple Rain?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Andrea Blue is a little lighter, more muted, cooler than Purple Rain.

Can I use Purple Rain instead of Andrea Blue?

The same difference applies the other way round: Purple Rain is a little darker, more saturated, 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.