Difference between Xms and Xmx and XX:MaxPermSize : <p>What the difference between</p>

<pre><code>-Xms4096m
-Xmx2048M 
-XX:MaxPermSize=712M
</code></pre>

<p>I am getting confused of this two <code>-Xmx2048M</code> and <code>-XX:MaxPermSize=712M</code>  </p>

<p>and will happen if I use -Xmx2048<code>M</code> or -Xmx2048<code>m</code></p>
