In trying to figure out the solution (no pun intended) to this problem: How can I get my Web API app to run again after upgrading to MVC 5 and Web API 2?, I realized that I have sort of brushed aside the relationship between packages and referenced assemblies (haven't given them much thought).
So what is the relationship? I manage packages with NuGet, and I manage assemblies via the context menu beneath the project's References folder, but I see on closer inspection that there seems to be a 1:1 correspondence between some of them.
e.g., I have Entity Framework in my NuGet Package Manager for my project, and I also have an assembly reference to EntityFramework. Yet this is correspondency does not extend across the board.
After all, after selecting the context menu item (I don't know if it's from Visual Studio or Resharper) "Remove Unused References," I have 14 Items referenced; but in the NuGet Package Manager, I have 30 packages listed in the "Installed Packages | All" tableau.
Yet, they all sport a "Manage" button when I highlight them; it seems that in other projects they say "Installed" with a green check mark or something...???