#! perl -slw
use strict;

die "Files differ in length"
    unless -s( $ARGV[0] ) == -s( $ARGV[ 0 ] );

open FH1, '<', $ARGV[0] or die $!;
open FH2, '<', $ARGV[1] or die $!;

#my $mismatch = 0;

until( eof( FH1 ) || eof( FH2 ) ) {
    my $line1 = <FH1>;
    my $line2 = <FH2>;
    next if $line1 eq $line2;
    my @line1 = split ' ', $line1;
    my @line2 = split ' ', $line2;
    for ( 0 .. $#line1 ) {
        next if $line1[ $_ ] eq $line2[ $_ ];
        next if abs( chop( $line1[ $_ ] ) - chop( $line2[ $_ ] ) ) < 2
            and $line1[ $_ ] eq $line2[ $_ ];

        die "Files differ at line: $. field: $_\n";
        #$mismatch = 1;
    }
}
#die "File are different\n" if $mismatch;

die "Files have different numbers of lines\n"
    unless eof( FH1 ) and eof( FH2 );

print "Files are the same\n"; ### Or "files are sufficiently similar"

close FH1;
close FH2;

##</code><code>##

C:\test>828506 file1 file2
Files are the same