I am trying to understand about Chrome (browser) development. I am very new to this and trying to figure out where to start in order to develop for Chrome Browser.
Just
To answer your first question this explains the differences between apps and extensions (I think there's no better way to explain their nature): https://developers.google.com/chrome/web-store/articles/apps_vs_extensions
What do you mean with "what kind of apps"? You can develop both hosted and packaged apps if is that what you intended, give a look at this: https://developers.google.com/chrome/apps/docs/index
Anyway the easiest way to start would be by building an extension, how-tos and good documentation makes it good to start with:
http://developer.chrome.com/extensions/getstarted.html