Different build errors between VisualStudio and Monodevelop

I'm new to programming and trying to create my game using C# and packages bought off the asset store. However, I'm getting build errors after I install some of these packages in a clean project. Is there why VisualStudio C# 2010 Express and Monodevelop would be giving different errors? For example, NGUI builds fine under Monodevelop but fails with 6 errors when attempting to build in Visual Studio. Other plugins have similar or opposite outcomes (Playmaker builds fine in VS but fails in Mono).

I will be contacting the devs of the various packages with these issues as well, but surely the issue something on my end. Have I set something up wrong? It seems odd that a package purchased from the asset store and installed into a clean project in the latest version of unity would fail to build.