The new version is extensible, so you can get access to the over 5,100 extensions in the Visual Studio ecosystem.[1]
It’s basically a full version of Visual Studio with no restrictions, except that you can’t use it in an enterprise setting and for teams with more than five people (you can, however, use it for any other kind of commercial and non-commercial project).
It's Visual Studio Professional with a different license. Previously you'd have paid through the nose for Visual Studio Pro, now it's free (subject to license conditions).
That was true of most of them through 2010 (though the 2008/2010 Web Developer Express supported, IIRC, at least C# and VB.NET as backend languages.), but not the 2012/2013 versions.
The VS2012/2013 Express Editions are not language specific, but project type specific -- the 2012 editions were "for Web", "for Windows 8" (i.e., Metro/Modern UI), "for Windows Desktop", and "for Windows Phone". 2013 merged "for Windows 8" and "for Windows Phone" into "for Windows".
It’s basically a full version of Visual Studio with no restrictions, except that you can’t use it in an enterprise setting and for teams with more than five people (you can, however, use it for any other kind of commercial and non-commercial project).
[1] https://visualstudiogallery.msdn.microsoft.com/