Updated iPad 2 Model From March 2012

[iLoner]

Out of curiosity, what is the difference between iPad 2 models produced in 2011 and those produced in March 2012? I have the more recent model, and I'd like to know what has been improved...

 

[J. A.]

Out of curiosity, what is the difference between iPad 2 models produced in 2011 and those produced in March 2012? I have the more recent model, and I'd like to know what has been improved...

The only hardware upgrade I found was a smaller version of the Apple A5 SoC.
See this article:

After the announcement and release of the third generation iPad, the iPad 2, which continues to be available for purchase received a hardware upgrade. The upgraded variant of the iPad 2 features a smaller version of the Apple A5 SoC, which is able to reduce battery consumption. Benchmark tests conducted by Anandtech concluded that the upgraded variant is able to last longer by at least an hour and a half, depending on the task that is conducted on the device. The maximum temperature that the device heated up to was also less than original iPad 2, tests conducted by the same organisation revealed that the upgraded variant was able to operate at 1 degrees lower when performing intensive tasks. Performance difference between the two variants, according Anandtech is negligible.
(Wikipedia)