case
when COL1 is NULL and B.COL2 is NULL then 'MATCHED'
when COL1=COL2 then 'MATCHING'
else 'NOT MATCHING'
end as STATUS

with function missing(
                      p_token_list1 varchar2,
                      p_token_list2 varchar2
                     )
       return varchar2
       is
           v_work_token     varchar2(4000);
           v_missing_tokens varchar2(4000);
           v_position       int;
       begin
           v_missing_tokens := ';' || p_token_list2 || ';';
           for v_i in 1..regexp_count(p_token_list1,';') + 1 loop
             v_work_token := ';' || regexp_substr(p_token_list1,'[^;]+',1,v_i) || ';';
             v_position := instr(v_missing_tokens,v_work_token);
             if v_position > 0
               then
                 v_missing_tokens := substr(v_missing_tokens,1,v_position) ||
                                     substr(v_missing_tokens,v_position + length(v_work_token));
             end if;
           end loop;
           return trim(both ';' from v_missing_tokens);
     end;
     t as (
           select  cola,
                   colb,
                   missing(colb,cola) missing_a,
                   missing(cola,colb) missing_b
             from  sample
          )
select  cola,
        colb,
        case
          when missing_a is not null then 'NOT MATCHING'
          when missing_b is not null then 'NOT MATCHING'
          else 'MATCHING'
        end matched,
        missing_a,
        missing_b
  from  t
/

COLA        COLB        MATCHED      MISSING_A       MISSING_B
----------- ----------- ------------ --------------- ---------------
abc;mno;def abc;def;xyz NOT MATCHING mno             xyz
efg         efg         MATCHING
def;abc     abc;def     MATCHING

SQL>

COLA                           COLB                           MATCHED              MISSING_A            MISSING_B           
------------------------------ ------------------------------ -------------------- -------------------- --------------------
abc;mno;def                    abc;def;xyz                    NOT MATCHING         xyz                  mno                 
efg                            efg                            MATCHED              (null)               (null)              
def;abc                        abc;def                        MATCHED              (null)               (null)              
(null)                         abc;def                        NOT MATCHING         abc;def              (null)              
(null)                         (null)                         MATCHED              (null)               (null)              
abc;def                        (null)                         NOT MATCHING         (null)               abc;def