There actually isn't a unibody (aluminum) MacBook anymore. It's the white plastic one. The 13" MacBook Pro is more comparable. I'm afraid I don't have the PDF info (Mactracker hasn't been updated yet). Below are the links to Apple's site:

MacBook: Apple - MacBook - Technical Specifications - Specs for the MacBook

13" MacBook Pro: Apple - MacBook Pro - Technical specifications of the 13-inch.