Marine Mist vs Hellbound Flesh

How close are they?

ΔE 16.9, loose: different enough that you should pick on purpose. Hellbound Flesh is a little darker, more muted than Marine Mist.

Can I use Hellbound Flesh instead of Marine Mist?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 17). Hellbound Flesh is a little darker, more muted than Marine Mist.

Can I use Marine Mist instead of Hellbound Flesh?

The same difference applies the other way round: Marine Mist 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.