title: What is the main technical difference between Web, Application, and Mobile programming?
body: <p>I want to know what is the main technical difference between Web (ASP, PHP, Ruby, etc.), 
  Application (C, C++, .NET, Java), and Mobile (J2ME, Objective C) programming, and which is the hardest.</p>
  
  <p>If someone learns one of these, can he easily switch over to one of the others?</p>