#!/usr/bin/perl

use strict;
use warnings;
use feature qw/say/;
use List::Compare;
use List::MoreUtils qw/uniq/;

my %hash1 = ("abc" => [1, 2, 3, 4]);
my %hash2 = ("abc" => [1, 3, 5, 7]);

$, = ",";

foreach my $key (uniq (keys %hash1, keys %hash2)) {
    my $lc = List::Compare->new($hash1{$key} // [], $hash2{$key} // []);

    say $lc->get_Lonly; # elements only in $hash1{$key}
    say $lc->get_Ronly; # elements only in $hash2{$key}
}