Like King Boo looks like a normal Boo with a crown, Queen Booline looks lik a normal Booline with a crown. Her crown is a silver version of Luigi Mansion's King Boo's and with a sapphire. She may be redisigned to look more like Luigi Mansion's King Boo after Luigi's Mansion: Dark Moon is released.
Queen Booline is the Castle boss of Yogurt Mountain in Mario 3D World. Originally, King Boo was the Castle boss, but he was moved to the fortress, who was originally Big Boo. Big Boo was then changed to a normal enemy.