The suggestion that using range(len()) is the equivalent of using enumerate() is incorrect. They return the same results, but they are not the same.
Using enumerate() actually gives you key/value pairs. Using range(len()) does not.
Let's check range(len()) first (working from the example from the original poster):
words = ['aba', 'xyz', 'xgx', 'dssd', 'sdjh']
print range(len(words))
This gives us a simple list:
[0, 1, 2, 3, 4]
... and the elements in this list serve as the "indexes" in our results.
So let's do the same thing with our enumerate() version:
words = ['aba', 'xyz', 'xgx', 'dssd', 'sdjh']
print enumerate(words)
This certainly doesn't give us a list:
<enumerate object at 0x7f6be7f32c30>
...so let's turn it into a list, and see what happens:
print list(enumerate(words))
It gives us:
[(0, 'aba'), (1, 'xyz'), (2, 'xgx'), (3, 'dssd'), (4, 'sdjh')]
These are actual key/value pairs.
So this ...
words = ['aba', 'xyz', 'xgx', 'dssd', 'sdjh']
for i in range(len(words)):
print "words[{}] = ".format(i), words[i]
... actually takes the first list (Words), and creates a second, simple list of the range indicated by the length of the first list.
So we have two simple lists, and we are merely printing one element from each list in order to get our so-called "key/value" pairs.
But they aren't really key/value pairs; they are merely two single elements printed at the same time, from different lists.
Whereas the enumerate () code:
for i, word in enumerate(words):
print "words[{}] = {}".format(i, word)
... also creates a second list. But that list actually is a list of key/value pairs, and we are asking for each key and value from a single source -- rather than from two lists (like we did above).
So we print the same results, but the sources are completely different -- and handled completely differently.