Aggregation is the relationship among the whole and a part. We can add/subtract some properties in the part (slave) side. It won't affect the entire part.
Best example is Car, which haves the wheels and some extra parts. Even though the parts are not there we can call it as car.
But, in the case of containment the entire part is affected when the part within that got affected. The human body is an apt example for this relationship. When the entire body dies the parts (heart etc) are died.