What is the difference between assimilation and accommodation in Piaget's theory?

Assimilation is the process of incorporating new experiences into existing mental frameworks, called schemas, without changing them. A child who calls all four-legged animals "doggy" is assimilating new animals into their existing dog schema. Accommodation is the process of modifying existing schemas or creating new ones to incorporate experiences that do not fit. When the child learns that a cat is different from a dog, they accommodate by creating a separate cat schema.