Python: What is the difference between a class variable and an instance variable?

1class User:
2    role = "user"  # Class variable
3
4    def __init__(self, name):
5        self.name = name  # Instance variable
6
7u1 = User("Alice")
8u2 = User("Bob")
9
10u1.role = "admin"  # Creates instance variable
11print(u1.role)  # "admin"
12print(u2.role)  # "user" (class variable)
13print(User.role)  # "user"