Final answer:
Preoperational children (2-7 years old) rely on personal knowledge and engage in pretend play, while concrete operational children (7-11 years old) can think logically, understand numbers, and grasp the concept of conservation.
Step-by-step explanation:
Preoperational children, who are typically between 2 and 7 years old, have not yet developed the ability to think logically or perform mental operations. They rely on their personal knowledge and experience to make sense of the world. They engage in pretend play and can use symbols to represent words and ideas.
On the other hand, concrete operational children, who are usually between 7 and 11 years old, can think logically about real events. They can understand numbers, perform mathematical operations, and grasp the concept of conservation. They are able to apply memory strategies and manipulate information in a logical way.
In summary, preoperational children are limited in their ability to think logically and mentally manipulate information, while concrete operational children have developed these skills and can think more logically and perform mental operations.