In [5]: list(set(temp1) - set(temp2))
Out[5]: ['Four', 'Three']
Beware that
In [5]: set([1, 2]) - set([2, 3])
Out[5]: set([1])
where you might expect/want it to equal set([1, 3]). If you do want set([1, 3]) as your answer, you'll need to use set([1, 2]).symmetric_difference(set([2, 3])).