Sandy is taller than all the other girls. Sandy is taller than any other girl.
The first would be more common, I think. With the second one (your example), it's a bit like saying "You can select any one girl from the class -- it doesn't matter which girl you pick -- and Sandy will be taller than she it."
Sandy is taller than all the other girls. Sandy is taller than any other girl.
The first would be more common, I think. With the second one (your example), it's a bit like saying "You can select any one girl from the class -- it doesn't matter which girl you pick -- and Sandy will be taller than she it."