Facebook share button anchor tag vs including javascript

What is different of having a facebook share button just by having an anchor tag:

<a href="http://www.facebook.com/sharer.php?u=<url 开发者_StackOverflowto share>&t=<title of content>">
  <img src="custom.jpg" />
</a>

than having one with the javascript provided by FB follow by the anchor tag?

<script src="http://static.ak.fbcdn.net/connect.php/js/FB.Share" type="text/javascript"></script>

I just want to verify I'm not missing any of the basic functionality of sharing a link by using the anchor tag only because I want to use the anchor tag way to customize my button image.

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The end result of the share is the same, as when you click the button it ends up taking you to the same endpoint. The difference is in how the button looks (and the count that shows up if that's the layout you've chosen).