[...]
my @arrays = (\@array1, \@array2, [...]);

my @union;
my @intersection;
my @difference;

my %counts;

foreach my $array (@arrays) {
    $counts{$_}++ foreach (@$array);
}

foreach my $item (keys %counts) {
    push @union, $item;
    push @{ $counts{$item} == scalar(@arrays) ? \@intersection : \@difference }, $item;
}