Computes the set-theoretic difference of two collections. The difference of two sets is all items that appear in the first set, but not in the second. If an item appears X times in the first set, and Y times in the second set, the difference contains the item X - Y times (0 times if X < Y). The source collections are not changed. A new collection is created with the difference of the collections; the order of the items in this collection is undefined.

Computes the set-theoretic difference of two collections. The difference of two sets is all items that appear in the first set, but not in the second. If an item appears X times in the first set, and Y times in the second set, the difference contains the item X - Y times (0 times if X < Y). The source collections are not changed. A new collection is created with the difference of the collections; the order of the items in this collection is undefined.