Pyrrhic Dawn vs Medium Flesh

How close are they?

ΔE 17.3, loose: different enough that you should pick on purpose. Medium Flesh is a little darker, cooler than Pyrrhic Dawn.

Can I use Medium Flesh instead of Pyrrhic Dawn?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Medium Flesh is a little darker, cooler than Pyrrhic Dawn.

Can I use Pyrrhic Dawn instead of Medium Flesh?

The same difference applies the other way round: Pyrrhic Dawn is a little lighter, 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.