What is the difference between Flex SDK 4.5.1.21328 and Flex SDK 4.5.1.21328A?
===

I have Flash Builder 4.5.1. This comes with Flex SDK 4.5.1.21328. A few of my colleagues have Flash Builder 6 which does not come bundled with Flex SDK 4.5.1.21328. 

Since we need to target the 4.5.1 SDK we downloaded it from [here][1]. However, the version available there is 4.5.1.21328A. We can only specific one target, Flex SDK 4.5.1.21328 or Flex SDK 4.5.1.21328A. 

What is the difference between Flex SDK 4.5.1.21328 and Flex SDK 4.5.1.21328A?

  [1]: http://sourceforge.net/adobe/flexsdk/wiki/Download%20Flex%204.5/