You can use the IN and NOT IN operators to check if the contents of one nested table appear or don't appear in the contents of another nested table.
SQL>
SQL> CREATE OR REPLACE PROCEDURE in_example AS
2 TYPE nestedTableType IS TABLE OF VARCHAR2(10);
3 myTable1 nestedTableType;
4 myTable2 nestedTableType;
5 myTable3 nestedTableType;
6 result BOOLEAN;
7 BEGIN
8 myTable1 := nestedTableType('A', 'B', 'C');
9 myTable2 := nestedTableType('D', 'E', 'F');
10 myTable3 := nestedTableType('A', 'B', 'C');
11
12 result := myTable3 IN (myTable1);
13 IF result THEN
14 DBMS_OUTPUT.PUT_LINE('myTable3 in myTable1');
15 END IF;
16
17 result := myTable3 NOT IN (myTable2);
18 IF result THEN
19 DBMS_OUTPUT.PUT_LINE('myTable3 not in myTable2');
20 END IF;
21 END in_example;
22 /
Procedure created.
SQL> CALL in_example();
myTable3 in myTable1
myTable3 not in myTable2
Call completed.
SQL>