my %hash;
@hash{@arr2}=(1) x @arr2;
my @cleaned=grep !$hash{$_},@arr1;

##</code><code>##

E:\Bin>perldoc -q "difference of two arrays"
Found in E:\Perl\lib\pod\perlfaq4.pod
  How do I compute the difference of two arrays?  How do I compute the intersection of two arrays?

            Use a hash. Here's code to do both and more. It assumes that
            each element is unique in a given array:

                @union = @intersection = @difference = ();
                %count = ();
                foreach $element (@array1, @array2) { $count{$element}++ }
                foreach $element (keys %count) {
                    push @union, $element;
                    push @{ $count{$element} > 1 ? \@intersection : \@difference }, $element;
                }

            Note that this is the *symmetric difference*, that is, all
            elements in either A or in B but not in both. Think of it as an
            xor operation.