Shen

Those are two different games. Different story, overworld, dungeons and items. In seasons, you control the seasons, and in ages, you can travel in time. The reason why those are a saga, because, if you finish one game you can continue it's story in the other. It will be a little different, and there will be references to the other game. You can even unlock things in the two game via passwords, if you continue it. via gamefaqs

Dzieki.