ΔE 29.9, loose: different enough that you should pick on purpose. Rotten Flesh is noticeably darker, much more muted, warmer than Ork Flesh.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 30). Rotten Flesh is noticeably darker, much more muted, warmer than Ork Flesh.
The same difference applies the other way round: Ork Flesh is noticeably lighter, much 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.
See Ork Flesh on the colour wheel See Rotten Flesh on the colour wheel
All matches: Ork Flesh equivalents · Rotten Flesh equivalents