#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

my @files = @ARGV;

my %people;

for my $file (@files) {
    open my $fh, '<', $file or die $!;
    <$fh>;  # Skip the header line.
    while (<$fh>) {
        chomp;
        my ($name, $job, $city, $state) = split /,\s*/;
        @{ $people{$name}{$file} }{qw{ job city state }}
            = ($job, $city, $state);
    }
}

for my $person (keys %people) {
    my $facts = $people{$person};
    my @changes;
    for my $fact (qw( job city state )) {
        push @changes, $fact
            if ($facts->{ $files[0] }{$fact} // "")
               ne ($facts->{ $files[1] }{$fact} // "");
    }
    say "$person =>",
        map {; " $_ Prev: ", $facts->{ $files[0] }{$_} // '-',
              ' Now: ', $facts->{ $files[1] }{$_} // '-'
        } @changes if @changes;
}