Refresh Vs Postback with Dynamic Controls

  I am looking for an explanation of the difference between a postback and a refresh.

  Please a little bit more than the obvious...

  I am looking to solve the following error that I am receiving.

  [HttpException (0x80004005): Failed to load viewstate.
  The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request. For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.

  I have closely followed several examples about the whidbey project and several other dynmic control examples.  

  The site for the most part is menu driven with a single page that differring ascx controls are loaded into the body of the page depending on the user selection.

  There are several controls that have a jump to another control.  Essentially removing themselves from the placeholder on the form and replacing with the next control.  This is used for a more fluid transition when values are passed from one screen to another.  Works well .... until someone does a refresh right after the jump.  Performing a postback then a refresh does not incurr the same error and completes successfully.  

  I have played with viewstate values but have not been able to terminate the problem.

  I would like to start with a discussion on the difference between the refresh and the postback if possible.

  I can post example code at a later time.