declare
        type coll is table of varchar2(200);
        source_table coll;
        target_table coll;
    begin
        select column_name bulk collect into source_table from all_tab_cols@remdb where table_name='SOURCE_TABLE';
        select column_name bulk collect into target_table from all_tab_cols where table_name='TARGET_TABLE';
        -- is source_table collection a subset of target_table collection?
        if source_table submultiset target_table then
            dbms_output.put_line('source table is a subset of target_table.');
            -- code for this case
        else
            dbms_output.put_line('source table is not a subset of target_table.');
            -- code here for this case
        end if;
    end;