Terracota vs Rebel Red

How close are they?

ΔE 15.9, loose: different enough that you should pick on purpose. Rebel Red is noticeably darker, cooler than Terracota.

Can I use Rebel Red instead of Terracota?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Rebel Red is noticeably darker, cooler than Terracota.

Can I use Terracota instead of Rebel Red?

The same difference applies the other way round: Terracota is noticeably lighter, 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.