Difference between SDSDX3-008G-P31 and SDSDX3-008G-A31?

I noticed both of these are selling online.  I know there was an Extreme III which was a Class 6 with 30MB rates.  I know there is the most recent model that is the Extreme which is a Class 10 with 30MB rates.  Which one is which and do they differ at all?  Can anyone clarify this question?

the last 3 digits are packing code. AXX is america PXX is Pacific Rim.