I've asked a question about what is "rendering a view". Got some answers:

Rendering a view means showing up a View eg html part to user or browser.

and

So by rendering a view, the MVC framework has handled the data in the controller and done the backend work in the model, and then sends that data to the View to be output to the user.

and

render just means to emit. To print. To echo. To write to some source (probably stdout).

but don't understand then the difference between rendering a view and using the Response class to send the output to the user using its sendResponse() method. If render a view means to echo the output to the user then why sendResponse() exists and vise versa? sendResponse() exactly sends headers and after headers outputs the body. They solve the same tasks but differently? What is the difference?