RegisterClientScriptInclude : It is similar to RegisterClientScriptBlock. but adds a script block that references an external .js file.
RegisterStartupScript : It add script block into the page, which executes once the page finishes loading but before Onload event raise of page onload. The script is not created as an event handler or function.
RegisterOnSubmitStatement : It add the script that executes in response to the page's onsubmit event.