Chef de cuisine is the traditional French term, meaning "chief of the kitchen" or "kitchen manager", from which the English word chef is derived. Head chef is often used to designate someone with the same duties as an executive chef but, in larger restaurants there is usually someone in charge of a head chef such a general manager, who makes executive decisions such as the direction of the menu, has final authority regarding staff hiring and management decisions and sets the overall tone and style of the restaurant.
Head chef is a title used to designate someone with similar responsibilities as an executive chef, but in larger restaurants, there's often a general manager who makes decisions like menu direction, staff hiring and management, and sets the restaurant's overall style.