1. A method for differential dynamic content delivery, the method comprising: providing a session document for a presentation, wherein the session document includes a session grammar and a session structured document; providing a session copy of a user profile including a user classification, creating a presentation control instruction, including: receiving from a user participating in the presentation a key phrase and optional parameters for invoking a presentation action; parsing the key phrase and parameters against a voice response grammar into a presentation control instruction; and the presentation control instruction includes a presentation action identifier and optional parameters; receiving, from a presenter, a user classification instruction to change a user classification in the session copy of a user profile; changing the user classification in the session copy of a user profile in dependence upon the presenter's instruction; selecting from the session structured document a classified structural element in dependence upon a user classification in the session copy of a user profile of a user in the presentation, the presentation action identifier, and the parameters received as part of the presentation control instruction; and presenting the selected structural element to the user.