Safety Orange vs Orange Flare

How close are they?

ΔE 15.9, loose: different enough that you should pick on purpose. Orange Flare is a little darker, cooler than Safety Orange.

Can I use Orange Flare instead of Safety Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Orange Flare is a little darker, cooler than Safety Orange.

Can I use Safety Orange instead of Orange Flare?

The same difference applies the other way round: Safety Orange is a little 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.