Lens Flare Glow vs Primary Yellow

How close are they?

ΔE 16.6, loose: different enough that you should pick on purpose. Primary Yellow is a little darker, warmer than Lens Flare Glow.

Can I use Primary Yellow instead of Lens Flare Glow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Primary Yellow is a little darker, warmer than Lens Flare Glow.

Can I use Lens Flare Glow instead of Primary Yellow?

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