I have two PLSQL Arrays of type nested table:

```
TYPE nested_typ IS TABLE OF VARCHAR2(21);

nt1 nested_typ := nested_typ('abc','def','123');
nt2 nested_typ := nested_typ('123');

```

I want to have the difference of these two collections, for above Ex: 'def', 'abc'

Please suggest any simple way to do this?

Thanks...