What is the difference between Petz Hamsterz Life 2 and Petz Hamsterz 2?

Information about these games is scarce, but the way I understand it the first game in the series was Hamsterz Life for the Nintendo DS. Then for some strange reason they made the sequel and called it Petz: Hamsterz Life 2 for the Gameboy Advance (which seems like a step backward). Then they decided to make a third game in the series, but they called it Petz: Hamsterz 2, because it was only the second game on the DS. A review of the most recent game can be found here...

http://ds.ign.com/articles/839/839645p1.html