Main differences are:
Google+ is new in the platform of social networks. It is in the experimental phase; on the other side Facebook has already near about 500 million members. Google+ has a number of new features, such as circles, sparks and hangouts that are missing on Facebook. In Google+ you can upload photos instantly where as in the case of Facebook it takes more time to upload. Face book have own branding as a social network but Google +does not mark as a social network. You can get dofollow backlinks from Google+.