What is the difference between permutations and combinations?

Permutations and combinations are two different ways of counting arrangements. Permutations consider the order of elements, so different orders of the same elements count as different permutations. Combinations, however, do not consider order, so only unique sets of elements are counted. For example, the permutations of {1, 2} are (1, 2) and (2, 1), while the combination is {1, 2}.