As the documentation mention :
When you call the redirect helper with no parameters, an instance of
Illuminate\Routing\Redirector is returned, allowing you to call any
method on the Redirector instance. For example, to generate a
RedirectResponse to a named route, you may use the route method
As you can see in the API methods(link below) there is a lot of methods that you can use and also there is one specific helper method home()
it's just a shortcut for redirect()->route('home') as highlighted by @ceejayoz.
Now the we will talk about return redirect('/');
and return redirect()->route('home');
the two of them redirects properly to the intended route as you said BUT the second one is really useful if in the future.
Why ?
Because if you want to change the URL structure in the routes file all you would need to change is the route only for example :
Route::get('/', 'IndexController@index')->name('home');
Will be :
Route::get('/home_page', 'IndexController@index')->name('home');
and all the redirects would refer to that route and there is no other thing that you should change => all redirects will still work perfectly.
BUT
If you choose to use the first one (i mean return redirect('/');
) then after the change in the route you will need to parse all your controllers to check if there is some redirects that uses then changed route and the change them :p