ScriptManager is an ASP.NET control that manages ASP.NET Ajax script libraries and is used for Ajax enabled controls, such as UpdatePanels
UpdatePanel is an ASP.NET AJAX control which allows page content to be updated asynchronously.
"In case if updatepanel takes more time to process set asyncpostbacktimeout property of your scriptmanager"
from question "Updatepanels stop working - possible session timeout"
from question "How interoperable are JQuery and Microsoft's AJAX UpdatePanel?"