RedirectToAction lets you construct a redirect url to a specific action/controller in your application, that is, it'll use the route table to generate the correct URL.Redirect requires that you provide a full URL to redirect to.
If you have an action 
Index on controller Home with parameter Id:- You can useRedirectToAction("Index", "Home", new { id = 5 })which will generate the URL for you based on your route table.
- You can useRedirectbut must construct the URL yourself, so you passRedirect("/Home/Index/5")or however your route table works.
- You can't redirect togoogle.com(an external URL) usingRedirectToAction, you must useRedirect.
RedirectToAction is meant for doing 302 redirects within your application and gives you an easier way to work with your route table.Redirect is meant for doing 302 redirects to everything else, specifically external URLs, but you can still redirect within your application, you just have to construct the URLs yourself.
Best Practices: Use 
https://www.dotnettricks.com/learn/mvc/return-view-vs-return-redirecttoaction-vs-return-redirect-vs-return-redirecttoroute
RedirectToAction for anything dealing with your application actions/controllers. If you use Redirect and provide the URL, you'll need to modify those URLs manually when your route table changes.https://www.dotnettricks.com/learn/mvc/return-view-vs-return-redirecttoaction-vs-return-redirect-vs-return-redirecttoroute
 
