Light Orange vs Fairy Flesh

How close are they?

ΔE 22.0, loose: different enough that you should pick on purpose. Fairy Flesh is much more saturated, cooler than Light Orange.

Can I use Fairy Flesh instead of Light Orange?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 22). Fairy Flesh is much more saturated, cooler than Light Orange.

Can I use Light Orange instead of Fairy Flesh?

The same difference applies the other way round: Light Orange is 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.