The "Subpage Default" is your default sub page and displays with a sidebar.  The "Subpage Fullwidth" displays the content full width.  The "Style Guide" page has been setup to display your site default styles.

The page will automatically display the page title at the top of the content area.  The checkbox "Hide Page Title" removes the title from the page.  The page description field is optional.

This template is setup as your default home page and works the same as your full width sub page.