Application pages are shared across all sites on the server, whereas a site page is specific to one site.
By default, most of the pages that appear when you create a SharePoint site are site pages. A site page can be added to a SharePoint page library. Users can customize a site page by using tools such as SharePoint Designer. A site page can also host features such as dynamic Web Parts, and Web Part Zones.
Application pages cannot do these things. However an application page is the best type of page to create if you want the page to contain custom code. Although you can add custom code to a site page, the code stops running when the user customizes the page by using tools such as SharePoint Designer. (Source)
You can create a Web Part Page and deploy it to the library