What is the similarity between the data structures dictionary and set?

The dictionary (dict) and set in Python share common features:

• Both use hash tables for data storage, ensuring fast access, addition, and removal of elements.
• Elements in a set and keys in a dictionary are unique.
• The order of elements in modern Python versions is preserved, but this is not the main similarity.

The main difference is that a dictionary stores key-value pairs, while a set contains only unique values without additional data.

Example:

my_dict = {'apple': 1, 'banana': 2}
my_set = {'apple', 'banana'}

print('apple' in my_dict)  # True
print('apple' in my_set)   # True

Thus, dictionaries and sets are similar in internal implementation and provide quick access to elements by key or value.