Find forskel mellem leder og forrige i resultattabel

$date2 = date_create($date2InString);
$date1 = date_create($date1InString);
date_diff($date2, $date1)->format('%h %i %s' );

for flere formater:http://php.net/manual/en/function .date-diff.php

nedenstående kode skulle gøre, hvad du bad om

$timestamp = strtotime($row['synd']);
 print '<tr>';
  print '<td>' .$row["ranking"].'</td>';
 print '<td>'.removeParanthesis($row["klass"]).'</td>';
   print '<td>'.$row["nimi"].'  '.$row["Perekonnanimi"].'</td>';
     print '<td>'.$date = date('d-m-Y', $timestamp).'</td>';
    print '<td>'.$row["teamnimi"].'</td>';
print '<td>'.$row["start"].'</td>';
print '<td>'.$row["finish"].'</td>';
print '<td>'.$row["aeg"].'</td>';
print '<td>'.$row["difleader"].'</td>';
print '<td>'.$row["difprev"].'</td>';
$date2 = date_create($row["difprev"]);
$date1 = date_create($row["difleader"]);
date_diff($date2, $date1)->format('%h %i %s' );
print '<td>'.$row["speed"].'</td>';
 print '</tr>';