why is index in for loop not the same python code example

Example 1: python3 iterate through indexes

items=['baseball','basketball','football']
for index, item in enumerate(items):
    print(index, item)

Example 2: python gt index in for cycle

my_list = [0,1,2,3,4]
for idx, val in enumerate(my_list):
    print('{0}: {1}'.format(idx,val))
#This will print:
#0: 0
#1: 1
#2: 2
#...

Example 3: for loop with index python3

colors = ["red", "green", "blue", "purple"]

for i in range(len(colors)):
    print(colors[i])