In my humble opinion destiny is the situation that comes to us, which are beyond our control. But our response to those situations is our choice/ freewill.

For example:

We didn’t choose our father ( 9th House).We were destined; that was our destiny; we were born.

We didn’t choose our appearance/ looks (1st House).

We didn‘t choose our children (5th House).

So situations are destiny. We didn’t choose them, they came to us.

Another Example:

If someone comes and insult you, you didn’t choose it, it came to you. This situation is destined. But your response to those situations is your choice/ freewill. What you choose is your choice/ freewill and once you choose it, that will decide your future destiny.

That’s why it is told that “Man is the maker of his own destiny”.