Here’s a comparison on a Mac Fanboy website. http://lowendmac.com/mail/0801mb/0122.html#1
Excerpt... “This is one seriously superior machine to Apple’s offering. The Apple has only two advantages: it’s 4 mm thinner (does anyone care?), and it runs Mac OS X. In every other respect it will be vastly outclassed by Lenovo’s latest.
I think my MacBook is wonderful, but I’m looking for a new machine that saves a couple pounds. Lenovo seems to have figured out the formula. Why can’t Apple?”
Metal weighs more, but it's the reason for the incredibly solid feel that reviewers have been fawning over. Oh, and you can actually buy a MacBook Air right now.