Hot Pink vs Spectral Purple

How close are they?

ΔE 31.1, loose: different enough that you should pick on purpose. Spectral Purple is a little darker, much more muted, cooler than Hot Pink.

Can I use Spectral Purple instead of Hot Pink?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 31). Spectral Purple is a little darker, much more muted, cooler than Hot Pink.

Can I use Hot Pink instead of Spectral Purple?

The same difference applies the other way round: Hot Pink is a little lighter, much 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.