Bound scripts are scripts tied into documents that gain special privileges over standalone scripts. They have special methods reference their parent document’s ID. Also they interact through custom dialogs, menus in the toolbar, and sidebar. The bound scripts’ script editor is hidden in the document’s main menu under Tools.
Standalone scripts typically serve for utility or as a library. While they do not have special methods like bound scripts, they appear as separate files in your Google Drive. Because of this, standalone scripts are flexible. Standalone scripts execute from within the development environment, triggers, as web-apps, or from another script. The GAS webpage provides a plethora of examples. Access standalone scripts via the Google Drive main menu or directly from here.
Tasker has many similarities to GAS as an automation platform. It is an Android automation application just as GAS provides automation for Google’s services. Tasker and GAS’ simplified coding environments provide many development tools. Similar to Google’s APIs, Tasker’s extensions and plugins extend functionality of Tasker itself. As a result of Tasker App Factory, creating Android applications is comparable to GAS web-apps. Additionally, homescreen shortcuts and child tasks are examples of utility type standalone scripts. And finally, plenty of online communities and resources help users in development.
More Google Apps Scripts Information
Also, see my tutorial on How To Use A Custom Menu To Execute Google Apps Scripts