Final answer:
The main difference lies in that Piaget's theory focuses on cognitive stages, while Vygotsky's theory emphasizes the sociocultural contexts of development.
Step-by-step explanation:
The main difference between Jean Piaget's theory and Lev Vygotsky's theory of development is that Piaget emphasized cognitive stages while Vygotsky focused on the sociocultural aspects of development. Piaget's theory of cognitive development contends that children move through a series of discrete stages characterized by qualitatively different types of thinking. This theory views development as a process that unfolds naturally according to a biological maturation timeline. In contrast, Vygotsky's sociocultural theory posits that development cannot be understood without considering the cultural and social context where it occurs. According to Vygotsky, cognitive development is largely the result of social interactions where learning is mediated by language and cultural artifacts, placing a significant emphasis on the role of social factors in the development of cognition.