The Wikipedia page on Chromium[0] gives some differences, though my remark was admittedly mostly based on the description of the chromium package in Debian[1], which at least claims ‘usage tracking’ (and the generally useless and backdoor-like auto-updater).
[0] https://en.wikipedia.org/wiki/Chromium_(web_browser)#Differe...
[1] http://packages.debian.org/wheezy/chromium