my @array = (
    [1,25],
    [3,7],
    [1,2],
    [2,4],
    [2,2]
);

foreach my $r( sort{ helper($a) <=> helper($b) }@array ){
    print Dumper $r;
}

# Betrag der Differenz berechnen
sub helper{
    my $ref = shift;
    return abs($ref->[1] - $ref->[0]); 
}