Pastel Peach vs Flat Flesh

How close are they?

ΔE 9.4, close: similar, with a visible difference side by side. Flat Flesh is a little darker, more muted than Pastel Peach.

Can I use Flat Flesh instead of Pastel Peach?

Usually, if you are not matching paint already on the model. Close match (ΔE 9). Flat Flesh is a little darker, more muted than Pastel Peach.

Can I use Pastel Peach instead of Flat Flesh?

The same difference applies the other way round: Pastel Peach is a little lighter, more saturated.

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.