Bright Shadow Flesh vs Rosy Flesh

How close are they?

ΔE 15.6, loose: different enough that you should pick on purpose. Rosy Flesh is a little lighter, much more muted than Bright Shadow Flesh.

Can I use Rosy Flesh instead of Bright Shadow Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Rosy Flesh is a little lighter, much more muted than Bright Shadow Flesh.

Can I use Bright Shadow Flesh instead of Rosy Flesh?

The same difference applies the other way round: Bright Shadow Flesh is a little darker, much 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.