Phoenix Red vs Light Orange

How close are they?

ΔE 22.5, loose: different enough that you should pick on purpose. Light Orange is noticeably lighter, more saturated, warmer than Phoenix Red.

Can I use Light Orange instead of Phoenix Red?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 23). Light Orange is noticeably lighter, more saturated, warmer than Phoenix Red.

Can I use Phoenix Red instead of Light Orange?

The same difference applies the other way round: Phoenix Red is noticeably darker, more muted, cooler.

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.