Generally speaking, if each element of set B is an element of set A, then it is said that B is a subset of A, and it is recorded as: B? One (or one? B), pronounced "B is contained in A" (or "A is contained in B")

And then what? It also represents a subset, but it represents proper subset.

Answer? B (or b? A): pronounced as "B really contains A" (or "A really contains B")

Therefore, there is only one difference between proper subset and subset: the subset can be A itself, but proper subset cannot be A. ..