Bright Red vs Phoenix Orange

How close are they?

ΔE 19.1, loose: different enough that you should pick on purpose. Phoenix Orange is noticeably darker, more muted than Bright Red.

Can I use Phoenix Orange instead of Bright Red?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 19). Phoenix Orange is noticeably darker, more muted than Bright Red.

Can I use Bright Red instead of Phoenix Orange?

The same difference applies the other way round: Bright Red is noticeably lighter, more saturated.

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.