ΔE 16.0, loose: different enough that you should pick on purpose. Heartfire is a little darker, more saturated, warmer than Phoenix Flames.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Heartfire is a little darker, more saturated, warmer than Phoenix Flames.
The same difference applies the other way round: Phoenix Flames is a little lighter, 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.
See Phoenix Flames on the colour wheel See Heartfire on the colour wheel
All matches: Phoenix Flames equivalents · Heartfire equivalents