You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <compare fromrevid="1" torevid="2" xml:space="preserve">&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Linje 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Linje 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;−&lt;/td&gt;&lt;td class='diff-deletedline'&gt;&lt;div&gt;&amp;lt;big&amp;gt;'''&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;MediaWiki&lt;/del&gt;-&lt;del class=&quot;diffchange diffchange-inline&quot;&gt;programvaren er nå installert&lt;/del&gt;.'''&amp;lt;/big&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td class='diff-addedline'&gt;&lt;div&gt;&amp;lt;big&amp;gt;'''&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;Toppsider.no &lt;/ins&gt;- &lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;presentasjoner av populære nettressurser&lt;/ins&gt;.'''&amp;lt;/big&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td class='diff-context'&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td class='diff-context'&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td class='diff-context'&gt;&lt;div&gt;Se [http://meta.wikimedia.org/wiki/Help:Contents brukerveiledningen] for informasjon om hvordan du bruker wiki-programvaren.&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;&amp;#160;&lt;/td&gt;&lt;td class='diff-context'&gt;&lt;div&gt;Se [http://meta.wikimedia.org/wiki/Help:Contents brukerveiledningen] for informasjon om hvordan du bruker wiki-programvaren.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
</compare>
</api>