You have one of the GSAs made by Datel before the sold Gameshark to Mad Catz. The GSA was originally made by Datel (who now makes the AR), but they sold it or something to MadCatz who started to use a different code format when they released the Gameshark SP.
The GSAs made by Datel use the same code format as the AR. Datel no longer makes GS anymore though. If you have one of the GSAs made by Datel, you can upgrade it into a AR but not all codes will work on a GSA upgraded into an AR since its not the real thing.
I'm going to have to say the AR is more reliable and less problematic. I don't have a GSSP or GSA, but based on what I've read from people who have a GSA/GSSP, they all have trouble getting most codes to work.