I am trying to find out exactly which iPod shuffle I have

I am trying to find out exactly which iPod shuffle I have. I have 2 that are 2nd generation (Model A1204). One has a part # of MB225LL/A and the other PB229LL/A. What is the difference? Thank you.

The first one is Silver and the 2nd is light green. Is there anything really different or just released later in the generation?

Thank You,

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