Claudia,
The templates home.php is the frontpage for all your posts. The template front-page.php is the frontpage of your complete site.
By default, all you posts are displayed on the homepage of your site. This means home.php is used. When you want to display a page as your homepage, you can decide to use a static homepage.
In order to create your homepage, you need all the code from home.php in front-page.php.
