Orange Flare vs Gold Yellow

How close are they?

ΔE 15.6, loose: different enough that you should pick on purpose. Gold Yellow is a little darker, much more saturated, warmer than Orange Flare.

Can I use Gold Yellow instead of Orange Flare?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Gold Yellow is a little darker, much more saturated, warmer than Orange Flare.

Can I use Orange Flare instead of Gold Yellow?

The same difference applies the other way round: Orange Flare is a little lighter, much 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.