Senshi Skin vs Ryn Flesh

How close are they?

ΔE 16.3, loose: different enough that you should pick on purpose. Ryn Flesh is a little lighter, more muted, warmer than Senshi Skin.

Can I use Ryn Flesh instead of Senshi Skin?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Ryn Flesh is a little lighter, more muted, warmer than Senshi Skin.

Can I use Senshi Skin instead of Ryn Flesh?

The same difference applies the other way round: Senshi Skin is a little darker, more saturated, 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.