What is the difference between Session and TempData in MVC?

Mentioned answer is wrong.
TempData object can be used across the controllers
Please follow below steps
public ActionResult Create(Movie movie)
{
@TempData["sData"] = "UserName";
return RedirectToAction("Welcome","HelloWorld");
}

HelloworldController.cs
Welcome.cshtml

<h2>Welcome @TempData["sData"]</h2>

The difference is once we used Tempdata not available for next use.

If you read the “TempData” and call the “Keep” method it will be persisted.

Ex;
@TempData[“Raghav”];
TempData.Keep(“Raghav”);

If you read “TempData” by using the “Peek” method it will persist for the next request.

Ex:
TestStr = TempData.Peek("Raghav").ToString();