The Essentials Server team have just published a blog post which gives you an at-a-glance look at what features are supported and not supported with the six current (and recently past) SBS and Essentials SKUs.
Read the blog post here – http://blogs.technet.com/b/sbs/archive/2015/07/23/client-connector-availability-with-windows-home-server-small-business-server-and-windows-server-essentials-for-supported-client-os.aspx