What are differences between piaget and erikson's work?
a. both study different aspects of human development.
b. each has a different number of stages in his theories.
c. each has different ideas about how people progress through stages.
d. all of the above.

The key difference between Piaget and Erikson is that Erikson created an understanding of development throughout the whole life, while Piaget focused just from infancy to the late teenage years. ... While Piaget focused on cognitive development, Erikson's thoughts were more focused on emotional development.