Ork Flesh vs Green Ghost

How close are they?

ΔE 15.4, loose: different enough that you should pick on purpose. Green Ghost is noticeably darker, more muted, cooler than Ork Flesh.

Can I use Green Ghost instead of Ork Flesh?

Not as a straight swap; see the closer alternatives below. Loose match (ΔE 15). Green Ghost is noticeably darker, more muted, cooler than Ork Flesh.

Can I use Ork Flesh instead of Green Ghost?

The same difference applies the other way round: Ork Flesh is noticeably lighter, 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.