Having own(ed) both, there is no comparison.
M3's rated at 333 HP, pushing 3400 lbs.
Z06's rated at 400 HP, pushing 3100 lbs.
Those numbers alone will tell you there's going to be quite a difference.
Real world experience:
Gladdo, at Cayuga would run high 13's with his E46 M3.
Same track, my average is a 12.7, with a best of 12.60. Little over 1 second may not seem like alot, but when your trapping at over 100 mph, 1 second is quite a bit.
The M3's quick off the line, but I found that once into 3rd gear, the M3 felt like it ran out of steam. The Z in comparison pulls hard, in any gear. Guess that's the effect of having 400 ft lbs. of torque will do for ya.