Rebel Red vs Primary Magenta

How close are they?

ΔE 15.1, loose: different enough that you should pick on purpose. Primary Magenta is a little lighter, more saturated than Rebel Red.

Can I use Primary Magenta instead of Rebel Red?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Primary Magenta is a little lighter, more saturated than Rebel Red.

Can I use Rebel Red instead of Primary Magenta?

The same difference applies the other way round: Rebel Red is a little darker, more muted.

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.