Okay, so if you can get the Lenovo at the price, it's the same for the two machines, so let's return to the key differences in the specs:
Add the mandatory $79 dongle to the rMB price. Size is irrelevant since LaVie has a bigger more useful 13.3" display at a lower weight (12" is too small for productivity) and built in ports so you don't have to deal with the bulk and hassle of a dongle that's easier to lose. Supposedly there's a model without multitouch that's even lighter at ~1.72# and less costly. The much faster CPU gets more work done per battery hour. Camera is 720p vs 480p. LaVie Z wins over the Macnetbook.