foreach my $unique (@second_list_new)
{
    if ($unique ~~ @first_list_new))
    {
        print "already there $unique\n\n";
    }
    else
    {
        print "newly in this $unique\n\n";
    }
}

##</code><code>##

    if (grep (/^\Q$unique\E$/,@first_list_new))

##</code><code>##

     my @first_list_new = map { s/\s*$//m; lc $_ } <FIRST_LIST>;