Here's another approach:

my @array_one = (2, 1, 3, 5);
my @array_two = (2, 3, 1, 0);

my %indices;
for my $i (0..3) {
    # store at which index the elements occurred
    push @{$indices{$array_one[$i]}}, $i;
    push @{$indices{$array_two[$i]}}, $i;
}

my ($same_pos, $diff_pos) = (0, 0);
for my $val (sort keys %indices) {
    my $i = $indices{$val};
    if (@$i >= 2) {
        if ($i->[0] == $i->[1]) {
            $same_pos++;
            print "element '$val' in same position\n";
        } else {
            $diff_pos++;
            print "element '$val' in different position\n";
        }
    }
}
printf "=> %d element%s in same position, %d element%s in different po
+sition\n",
        $same_pos, $same_pos==1 ? "":"s",
        $diff_pos, $diff_pos==1 ? "":"s";
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Output:

element '1' in different position
element '2' in same position
element '3' in different position
=> 1 element in same position, 2 elements in different position
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Note that this assumes that an element occurs in either the same or in a different position, but not both (and that there's no more than one occurrence of each element within one array). I.e. something like this

  3, 1, 3, 5
  3, 3, 1, 0
[download]

will produce ambiguous output (report the first occurrence, that is).