An "App" is nothing more than a dedicated link to a specific Internet site, no matter what device you use to access the internet. "Apps" will navigate the user directly to the specific Web site, are developed in such a way that the Web site's system will determine how to render the display on the device being used, where as a conventional Web site will render the display in full desktop view. If accessing through a mobile device, the desk top presentation will not display the full screen, only what the window of the users device will permit making it necessary for the consumer to move the browser window around to see the Web page. You will not see the entire page at once without sliding it up and down or side to side.
Apps may also direct you to a stripped out version of the full website to accommodate for a small resolution like on an IPhone. Other than this there really is no difference between an App and searching yourself on Google for the full website.
