Link1: http://docs.joomla.org/J2.5:Developing_a_MVC_Component/Adding_backend_actions#Adding_an_editing_view
Link2 :http://docs.joomla.org/J2.5:Developing_a_MVC_Component/Adding_a_view_to_the_site_part#Setting_the_view
In the above two links Link1 view is calling edit.php to display the view and in LinK2 is using default.php to display the view.
Now my question is that which thing is forcing these two views to use different files i.e. default.php and edit.php, though structure of these two views is almost same
In Joomla component you can set different layouts
for your component.
here two different layout is used default and edit so you can set layout by using
index.php?option=com_helloworld&layout=edit
Also you can set the layouts from your view.html.php
$this->setLayout("layout name");
hope its helps..