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;Řádka 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Řádka 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;#160;&lt;/div&gt;&lt;/td&gt;&lt;td class='diff-marker'&gt;+&lt;/td&gt;&lt;td class='diff-addedline'&gt;&lt;div&gt;&lt;ins class=&quot;diffchange diffchange-inline&quot;&gt;To get the logo in the right place under this skin, see the code in [http://de.furry.wikia.com/wiki/MediaWiki:Monobook.css de:MediaWiki:Monobook.css]. --[[User:GreenReaper|GreenReaper]]&amp;lt;sup&amp;gt;([[User talk:GreenReaper|talk]])&amp;lt;/sup&amp;gt; 00:04, 14. 8. 2007 (UTC)&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
</compare>
</api>