This is a popular question in.NET job interviews, as I've heard from several acquaintances. Developers with limited hands-on expertise with MVC should be able to respond to the question because the scenario is typical and requires returning anything from the controller to the presentation environment on a regular basis. We are extremely familiar with the "ActionResult" class, which is the base class for many classes and can return an object from those classes. The class structure is as follows:

System.Object
System.Web.Mvc.ActionResult

    System.Web.Mvc.ContentResult
    System.Web.Mvc.EmptyResult
    System.Web.Mvc.FileResult
    System.Web.Mvc.HttpStatusCodeResult
    System.Web.Mvc.JavaScriptResult
    System.Web.Mvc.JsonResult
    System.Web.Mvc.RedirectResult
    System.Web.Mvc.RedirectToRouteResult
    System.Web.Mvc.ViewResultBase

In this example, we will see all of the derived classes that is inherited from the “ActionResult” base class. So, let's start one by one.
 
Return View
This is a most common and very frequently used type. We see that we can pass eight parameters when we return the view. We can specify the view name explicitly or may not.

Return partial View

The concept of a partial view is quite similar to the master page concept used in Web Form applications. The partial view is simply a pagelet that may be returned from the controller and combines with the main view to create a single tangible HTML page.

It may require four parameters to render in the partial view.
 
Redirect
This is comparable to the Response.redirect() and Server.Transfer() routines. It uses the URL path to redirect, however with MVC, we can instead use Response.Redirect() or Server.Transfer() instead.

Redirect To Action
Sometimes it is necessary to call another action after completion of one action, this is very similar to a function call in traditional function oriented programming or Object Oriented Programming. It may take 6 parameters. The first parameter is very simple, only action name.

Return content
This is useful when we want to return a small amount of strings from a controller/action. It takes three parameters. The first one is a simple string and the remaining two are strings with little information.

Return JavaScript
When we wanted to return a JavaScript string, we may use this function. It takes only one parameter, the string only.

Return File
We are allowed to return a binary file if needed from a controller. It takes 6 parameters maximum.

Conclusion
Those are all of the return types in an action in an MVC controller, but we rarely use them; in my limited experience, users prefer to return View() from the action. What say you? Have fun learning.

ViewResult and ActionResult are two classes in ASP.NET MVC that are used to display the output of an action function.

1. Action-Result
For all action result kinds in ASP.NET MVC, ActionResult is the abstract base class. It serves as the foundation class for many result kinds, including JsonResult, ViewResult, and RedirectResult. Usually, you specify ActionResult as the return type when you define an action method in a controller.

As an illustration

public ActionResult MyAction()
{
    // Action logic here
    return View(); // Returns a ViewResult
}

2. ViewResult
ViewResult is a specific type of ActionResult that represents a result that renders a view. When you return a ViewResult from an action method, it means that the framework should render a view associated with the action.

For example

public ViewResult MyAction()
{
    // Action logic here
    return View(); // Returns a ViewResult
}

Key differences in nutshell

The following are the key differences in nutshell.

• ActionResult is more general: ActionResult is a more general type, and it can represent different types of results, not just views. It allows for flexibility in returning various result types.
• ViewResult is specific to views: ViewResult is a specific type derived from ActionResult and is used when you specifically want to return a view from an action method.
• ViewResult simplifies return type: If your action method is intended to return a view, using ViewResult directly can make your code more explicit and easier to understand.
• ActionResult provides more options: If your action method needs to return different types of results based on certain conditions, using ActionResult allows you to return different types of results (e.g., RedirectResult, JsonResult, etc.) from the same action.

Moreover, in practice, you can often use ViewResult directly when you know your action will always return a view. If you need more flexibility or want to return different types of results, using ActionResult allows for that versatility.