Google's Google+ has been growing rapidly & is one of the top growing social networks. Google's buzz & wave both failed to tap into the social networking space. Facebook stole the show from Myspace & is the biggest social network. Some of the top differences between the 2 are
1) With Google+ circles, you can target & communicate the message. While facebook doesn't have the option to target a particualr group. Segment communications in Google+.
2) Google+ is currently open for personal accounts only. While facebook is open for both personal & Business accounts.
3) Sharing information - Google+ provides an easy way to share the information through circles. Facebook has a limit on the number of words which can be posted.
4) Optimized Google+ pages will have the advantage of listing in Google search results & this can drive traffic to the pages. This is a big drawback for facebook pages.
5) Hangouts – Hangout is already turning out be the great asset for Google+. With a webcam & mic, one can chat with people in Google+ & also do the video chatting.