I recommend the use of Apache Cordova, which using HTML5/javascript allows for building apps for many different smartphones Android, FirefoxOS, Iphone, Blackberry etc . Cordova enables to target many platforms at once and simultaneously eliminate the need to know any sort of specific native programming for the host environment, other than some basic building-IDEs and choosing cordova plugins which abtract away platform differences for various features, ex plugins for device_info/location/push notifications etc.

A app does more than opening in a browser, such as caching and offline reading/editting.