n python 2.x range() returns a list and xrange() returns an xrange object, which is kind of like an iterator and generates the numbers on demand.(Lazy Evaluation)
In [1]: range(5)
Out[1]: [0, 1, 2, 3, 4]
In [2]: xrange(5)
Out[2]: xrange(5)
In [3]: print xrange.__doc__
xrange([start,] stop[, step]) -> xrange object
Like range(), but instead of returning a list, returns an object that
generates the numbers in the range on demand. For looping, this is
slightly faster than range() and more memory efficient.
In python 3.x xrange() has been removed and range() now works like xrange() and returns a range object.
In [4]: range(5)
Out[4]: range(0, 5)
In [5]: print (range.__doc__)
range([start,] stop[, step]) -> range object
Returns a virtual sequence of numbers from start to stop by step.
