雪梨 is one type of Pear
I think the 雪梨 you called, also called 鸭梨 by other people.
sometimes people use it for desert or soup or just 雪梨水
The name of that type of 梨 called Chinese White Pear or Ya Pear.
You can check this website for more information:
http://www.wingmau-fruit.com/fruit/ya_pear.htm