Are the techinical programming/ coding for mobile very different from web app? Are mobile apps more costly and more complex compared to web apps? For eg. Farmville (by Zynga) game for facebook on the web compared to Farmville game on mobile phone.
Unlike web app, mobile app has direct access to disk, filesystem, and other resource. Web app runs in a "sandbox". Web app runs on the fly and it needs to be downloaded every time it runs. Other than that, there is not much different. With the advent of cloud computing, the difference is even smaller
Right. And using some latest app development libraries (JavaScript/CSS), one can even create web apps that could be installed locally (for offline use), with native look-n-feel. Native apps are certainly costlier in an enterprise environment as there is a learning curve attached (programming language, SDK, etc.). Whereas one can easily create web apps using commonly known web techs such as HTML, JS, CSS, PHP, etc.
It really depends on what mobile device you are developing for iOS apps may be considered to be more time consuming due to the Objective-C/Cocoa learning curve also you have to pay apple for the developer kit/rights. Android apps on the other hand are Java based and free to develop. Web apps are also complex depending on what you want to do its really a matter of what you already know and how much you are willing to learn as well as how quickly you learn to really tell you which is more time consuming.