Flickering Flame vs Fire Orange

How close are they?

ΔE 17.8, loose: different enough that you should pick on purpose. Fire Orange is a little darker, more muted, cooler than Flickering Flame.

Can I use Fire Orange instead of Flickering Flame?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 18). Fire Orange is a little darker, more muted, cooler than Flickering Flame.

Can I use Flickering Flame instead of Fire Orange?

The same difference applies the other way round: Flickering Flame is a little lighter, more saturated, 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.