Different in Annotation Symfony 2 / Doctrine 2

What is the difference between these two?

/**
* @ORM\ManyToOne(targetEntity="Category", inversedBy="products",cascade={"remove"})
* @ORM\JoinColumn(name="category_id", referencedColumnName="id") 
*/
protected $category;

and

/**
 *
 * @ORM\ManyToOne(targetEntity="Category", inversedBy="products")
 * @ORM\JoinColumn(name="category_id", referencedColumnName="id", onDelete="CASCADE"))
 */
protected $category;

Thanks !