The Launch plug-in is displayed when you choose Launch in the Notifier Kind pop-up menu in the Notifier Info pane.
Just the Application | will start or switch to the specified application without any associated document. This is equivalent to double-clicking on the application in the Finder. |
Document With Default Application | will cause the specified document to be opened in whatever application is its default. This is equivalent to double-clicking on the document in the Finder. |
Document With Specified Application | will start or switch to the specified application, and open the specified document in that application. This is equivalent to dragging the document onto the application in the Finder. |