title: What are diffs between iOS App (Xamarin) vs. iOS XAML App (Xamarin.Forms) vs. Cross-Platform
body: <p>What is the difference between these Visual Studio 2017 new project options?<br>
  File > New > Project > Visual C# > …<br>
  OPTION 1. > Cross-Platform       which supports iOS, Android, etc.<br>
  OPTION 2. > iOS Extensions<br>
  OPTION 3. > iPhone &amp; iPad > iOS App (Xamarin)<br>
  OPTION 4. iOS XAML App (Xamarin.Forms)  </p>
  
  <p>I want to make an app on iPad that displays live images from a remote USB camera, via a socket.  Later to also run on iPhone, Android, and Windows 10.</p>