Bright Orange vs Flat Flesh

How close are they?

ΔE 6.8, close: similar, with a visible difference side by side. Flat Flesh is warmer than Bright Orange.

Can I use Flat Flesh instead of Bright Orange?

Usually, if you are not matching paint already on the model. Close match (ΔE 7). Flat Flesh is warmer than Bright Orange.

Can I use Bright Orange instead of Flat Flesh?

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