12 possibilities for the winner
11 possibilities for 2nd place
10 possibilities for 3rd place
if the winning employees were a, b, and c in that order, that would not be the same as b, c, and a in that order.
when order matters, you are dealing with a permutation.
in the second problem, order does not matter ...
nurses a, b, and c are in the same group as nurses b, c, and a
when order does not matter, you are dealing with a combination.