The non-provisional can indeed be different from the provisional. It can have its own new claims, new drawings, new description, etc. The risk here is that if you add in a new idea or new feature when you file the non-provisional, that new feature will only get the benefit of the later filing date of the new non-provisional application. In other words, since you did not include that new idea or new feature when you filed your provisional, that patent office will not give you credit for it all the way back in time to the date you filed the provisional.
Kind regards,
Brad