"Carte du jour" translates "card of the day" and is usually used as the menu of the day in French dining (think "daily special" in diner food).
the plat du jour in French translates as todays' special. In a plat du jour menu, you have no change option (unless you pay more).
Du Jour menu is a French term reffering to daily specials. The phrase means of the day.
Du jour means of the day. as in soup du jour.
It is the menu for the day; literally "card of the day."