What is the difference between google buzz and google plus

Google buzz is no more ! Google Buzz was a social networking, microblogging and messaging tool that was developed by Google and On October 14, 2011, Google announced that it would be discontinuing the service and that the existing content would be available in read-only mode. Buzz was discontinued on December 15, 2011. And now Google offering people to use Google plus as a social networking service !