Answer:
A permutation is an arrangement of all or part of a set of objects, with regard to the order of the arrangement. Each possible arrangement would be an example of a permutation.
The complete list of possible permutations would be:
AB, AC, BA, BC, CA, and CB.
Permutation is used for lists (order matters) and Combination for groups (order doesn't matter). Famous joke for the difference is: A “combination lock” should really be called a “permutation lock”. The order you put in the numbers of lock matters.