Difference between Corona, Phonegap, Titanium

1. 
   PhoneGap is not just a native wrapper of a web app. Through the PhoneGap javascript APIs, the "web app" has access to the mobile phone functions such as Geolocation, Accelerometer Camera, Contacts, Database, File system, etc. Basically any function that the mobile phone SDK provides can be "bridged" to the javascript world. On the other hand, a normal web app that runs on the mobile web browser does not have access to most of these functions (security being the primary reason). Therefore, a PhoneGap app is more of a mobile app than a web app. You can certainly use PhoneGap to wrap a web app that does not use any PhoneGap APIs at all, but that is not what PhoneGap was created for.
   
2. Titanium does NOT compile your html, css or javascript code into "native bits". They are packaged as resources to the executable bundle, much like an embedded image file. When the application runs, these resources are loaded into a UIWebView control and run there (as javascript, not native bits, of course). There is no such thing as a javascript-to-native-code (or to-objective-c) compiler. This is done the same way in PhoneGap as well. From architectural standpoint, these two frameworks are very similar.
   
    3. Corona SDK is a software development kit created by Walter Luh, co-founder of Corona Labs (formerly known as Ansca Mobile). It allows software programmers to build mobile applications for the iPhone, iPad, and Android devices.
   Corona lets developers use integrated Lua, layered on top of C++/OpenGL, to build graphically rich applications that are also lightweight in size and quick in development time. The SDK does not charge per-app royalty or impose any branding requirement, and has a subscription-based purchase model that allows new features to be rolled out immediately to users.