Variations Take a set A of n different elements. Choose p elements in a specific order. Each such choice is called a variation of n elements choose p. Well, there are n possibilities to choose the first element. There are n-1 possibilities to choose the second element.
Permutations Take a set A of n different elements.
Choose the n elements in a specific order. Each such choice is called a permutation of n elements. From above we know that such permutation is a variation of n elements, taking all the elements in a specific order. Combinations Take a set A of n different elements. Choose a subset of p elements.