UML aggregation vs association

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Maybe this can help you, but i don’t think you will find the perfect explanation:

The difference is one of implication. Aggregation denotes whole/part
relationships whereas associations do not. However, there is not
likely to be much difference in the way that the two relationships are
implemented. That is, it would be very difficult to look at the code
and determine whether a particular relationship ought to be
aggregation or association. For this reason, it is pretty safe to
ignore the aggregation relationship altogether.
[Robert C. Martin | UML]

And an example for each situation:

a) Association is a relationship where all object have their own
lifecycle and there is no owner. Let’s take an example of Teacher and
Student. Multiple students can associate with a single teacher and
single student can associate with multiple teachers, but there is no
ownership between the objects and both have their own lifecycle. Both
can create and delete independently.

b) Aggregation is a specialized form of Association where all object have their own lifecycle but there is ownership and child
object can not belong to another parent object. Let’s take an example
of Department and teacher. A single teacher can not belong to
multiple departments, but if we delete the department, the teacher object
will not be destroyed. We can think about “has-a” relationship.
[Maesh | GeeksWithBlogs]

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