<p>I have two strings</p>

<pre><code>&lt;EM&gt;is &lt;i&gt;love&lt;/i&gt;&lt;/EM&gt;,&lt;PARTITION /&gt;
</code></pre>

<p>and</p>

<pre><code>&lt;EM&gt;is &lt;i&gt;love&lt;/i&gt;,&lt;PARTITION /&gt;
</code></pre>

<p>I want a regex to match the second string completely but should not match the first one.  Please help.</p>

<p>Note: Everything can change except the EM and PARTITION tags.</p>

I don't think you're asking the right question.  This regex matches the second string completely and not the first:
```
/^<EM>is <i>love<\/i>,<PARTITION \/>$/
```
But obviously, you want to match a class of strings, not just the second string... right?  Define the class of strings you want to match and you can be 1 step closer to getting the regular expression you need.