Feywild Glow vs Ambush Yellow

How close are they?

ΔE 20.5, loose: different enough that you should pick on purpose. Ambush Yellow is a little darker, much more saturated, cooler than Feywild Glow.

Can I use Ambush Yellow instead of Feywild Glow?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 21). Ambush Yellow is a little darker, much more saturated, cooler than Feywild Glow.

Can I use Feywild Glow instead of Ambush Yellow?

The same difference applies the other way round: Feywild Glow is a little lighter, much more muted, 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.