When we talk about the difference between two sets or arrays, we are referring to all the elements of the first array that don't appear in the second array. In essence, all the elements in the first array that are not common to the second array are referred to as the difference between the two sets. The difference in sets p and q, for example, will be denoted by p – q.
If array p, for example, has the elements {1, 2, 3, 4}, and array q has the elements {2, 4, 5, 6}, then the difference between the two arrays, p - q, will be {1,3}. Let's find out how this is done.