Vivid Flesh vs Old Rose

How close are they?

ΔE 15.8, loose: different enough that you should pick on purpose. Old Rose is a little darker, much more muted, cooler than Vivid Flesh.

Can I use Old Rose instead of Vivid Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Old Rose is a little darker, much more muted, cooler than Vivid Flesh.

Can I use Vivid Flesh instead of Old Rose?

The same difference applies the other way round: Vivid Flesh is a little lighter, much more saturated, 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.