Your comparision is in SCALAR context. So it would always compare only the number of elements in the Two arrays. So it's better to do it on line at a time.

$index = 0;
while($raw_data_Actual[$index] ne "" or $raw_data_Expected[$index] ne 
+""){
if($raw_data_Actual[$index] ne $raw_data_Expected[$index]){
print"Fail: $raw_data_Expected[$index]";
last;
$index++;
}
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This just one of the solution. There is always more than one way to solve a problem.