The preview combines all settings and changes from the different sub-menu tabs (´Settings´, ´Start´, ´Hotspots´, ´Auto Pilot´ etc.). This is useful, as you won´t be able to see the combination of all your settings in the viewer from within the program (i.e. you won´t be able to see both hotspots and lens flare effects at the same time, unless you click ´Preview´or you publish your virtual tour).