Who knows how to use SPMicroFeedManager and what the relationship between SocialFeed and MicroFeed?

As we know, we can use SPSocialFeedManager to get the NewsFeed in SharePoint 2013. But I also see SPMicroFeedManager is exsiting in Microsoft.Office.Server.UserProfiles. I'm wondering what the difference is between SPSocialFeedManager and SPMicroFeedManager. And how to use SPMicroFeedManager as well.

In addition, can I get the NewsFeed based on a Site? When I tried to use SPSocialFeedManager to get the NewsFeed, it retrieved all the SocialThreads from all the sites (including personal and normal sites) even there was no NewsFeed in the current site which I used to construct SPServiceContext object.

Any ideas about the questions above?