I would probably use something like this.

The first foreach creates a hash that contains all of the keys that are present in hash one and hash two who's contents dont match. It's data element is a list where $differences{$_}[0] is the data from hash one and $differences{$_}[1] is the data from hash two. It also has an entry for each key in hash one that does not appear in hash two, where $differences{$_}[1] is undefined.

The second foreach performs the inverse using the keys of hash two. except that when a key in hash two is not present in hash one, $differences{$_}[0] is undefined and $differences{$_}[1] contains the data from hash two. When it is complete %differences contains 3 types of record:

• key appears in both hashes, but the data is different.
• key appears in first hash, data in $differences{$_}[0], $differences{$_}[1 ] is undefined.
• key appears in second hash, data in $differences{$_}[1], $differences{$_}[0 ] is undefined.

my %differences = ();
foreach (keys %hash1) {
    $differences{$_}= [$hash1{$_}, $hash2{$_}] if $hash1{$_} ne $hash2
+{$_};
};
foreach (keys %hash2) {
    $differences{$_}= [$hash1{$_}, $hash2{$_}] if $hash1{$_} ne $hash2
+{$_};
};
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Nuance