ΔE 45.5, loose: different enough that you should pick on purpose. Zombie Skin is a little lighter, much more muted, warmer than Shamrock Green.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 46). Zombie Skin is a little lighter, much more muted, warmer than Shamrock Green.
The same difference applies the other way round: Shamrock Green is a little darker, 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 Shamrock Green on the colour wheel See Zombie Skin on the colour wheel
All matches: Shamrock Green equivalents · Zombie Skin equivalents