The difference between a formal dining room and an informal one exists.
Whereas any informal dining room is the part of a living room, a kitchen, or even your home office or a kids room the formal room is a separate one. Of course the existence of such a room becomes possible only in large houses, having more than one bedroom. Any room may be designed as a formal one. The best one is the room which is not a pass-through area. It needs to have a separate door and furnished with a formal dining room set. As a rule formal dining room sets remind contemporary furniture. You may confuse a formal dining room table and a good quality modern table which is made from wood. The shapes of formal furniture are mostly simple. The table is rectangular and long.
The formal dining room chairs should have tall backs. When you furnish a formal dining room do not forget about window treatments and accessories. Choose long curtains. Avoid cool colors giving preference to pastel warm tones. The red color shapes stimulate appetite, but too much red may cause aggression. Thus, mix warm colors when decorating your room where you gather to take a dinner. The formal room for dining needs a chandelier. A classic semi-sized chandelier is perfect. As the formal dining room is a separate area, you may choose for it a design which differs from the main home interior design.