The difference between the Secure Node and the Secure Application is the extent to which the underlying operating system and other environment are secured.  A Secure Node includes all aspects of user authentication, file system protections, and operating environment security.  The Secure Application is a product that does not include the operating environment.  The Secure Application provides security features only for the application features.  See section 9.7 for the relationships among a Secure Node, Secure Application, and other actors.