The main difference between deepcopy() and copy() in Python lies in how they handle nested objects. The copy() function creates a shallow copy, meaning it duplicates the outer object but not the nested objects within it. If you modify a nested object in the shallow copy, the changes will also affect the original object because they both reference the same inner object.

On the other hand, deepcopy() from the copy module creates a deep copy, meaning it duplicates the outer object as well as all nested objects. This results in completely independent objects, so changes to the deep copy will not affect the original object, even for nested structures.

For instance, if you have a list of lists, using copy() will only copy the outer list. The inner lists will still refer to the same memory location as in the original object. In contrast, deepcopy() will create entirely new inner lists.

Understanding the distinction between these two functions is critical when dealing with complex data structures in Python. If you're considering a python certification course, learning concepts like deepcopy() and copy() will deepen your understanding of memory management, an essential skill for professional development.