A royal mantle, or more simply a Mantle, is a garment normally worn by emperors, kings or queens as a symbol of authority. When worn at a coronation, such mantles may be referred to as coronation mantles. Many princes also wear such a mantle.

The Robe Royal (also known as the Pallium Regale, Imperial Mantle or Dalmatic Robe) is a robe worn by the British monarch when they are crowned at their coronation. It is donned just before the monarch is invested with the Orb, Ring and Sceptres. It is worn during the crowning and paying of homage.

The king in your picture is wearing a royal robe or royal garments. Kings and Queens today wear pretty much what ordinary people wear, uniforms, suits, gowns, dresses, suits, maybe even more casual clothes. When they are being crowned, they wear coronation robes.

Around his neck, the king will wear the Royal Stole, a thin band of golden silk generously embroidered with heraldry and foliage. And draped over his shoulders will be the Imperial Mantle.