Two tables align in different ways with the same stylesheet - php

Question

I have two tables. One is created with html (and a little bit of php) while the other is created by two php-loops.
First of all, the stylesheet:
.statistics {
font-family: Arial, monospace;
font-size: 36px;
margin-left: 5%;
width: 90%;
}
.statistics tr {
line-height: 50px;
}
.statistics th {
text-align: center;
}
.statistics td {
text-align: center;
}
button {
margin-left: 25%;
width: 50%;
height: 40px;
border: none;
border-radius: 20px;
font-family: Arial, monospace;
font-size: 20px;
}
The following table is aligned properly:
<table class="statistics">
<tr>
<th>Benutzer</th>
<th>Artikel</th>
<th>Reservierungen</th>
</tr>
<tr>
<td><?php echo $client->statistic_getAmount();?></td>
<td><?php echo $articles->statistic_getAmount();?></td>
<td><?php echo $reservations->statistic_getAmount();?></td>
</tr>
<tr>
<th>Seiten (.php)</th>
<th>Datenbankeinträge</th>
<th>Zeilen mit Code</th>
</tr>
<tr>
<td>18</td>
<td>27</td>
<td>4407+</td>
</tr>
</table>
While this one isn't aligned properly:
<form method="post" action="webinterface.php" class="perms">
<table class="statistics">
<tr>
<th>Benutzer</th>
<?php
foreach ($permgroupa as $group) {
echo "<th>".$group."<th>";
}
echo "</tr>";
$users = $client->getUsers();
while ($row = mysqli_fetch_assoc($users)) :?>
<tr>
<td><?php echo $row['username'];?></td>
<?php foreach ($permgroupa as $group) : ?>
<td><input type="checkbox" name="<?php echo $group;?>-<?php echo $row['username'];?>" <?php if ($perms->hasPermission($row['username'], $group)) {echo "checked";}?>></td>
<?php endforeach;?>
</tr>
<?php endwhile;?>
</table><button type="submit" class="btnalter" name="alterrights">Rechte aktualisieren</button></form>
The tables in action
Does someone know, why they align in different ways?

Answer 1

1 - don't put your table inside a form
2 - the number of columns is not the same for the first and the second table