What is the difference between old Tata Zest and new Tata Zest?

This is the first time that Tata have launched Zest and as it is a completely new product and hence there isn't any old Zest to compare with. Though, Zest have Tata Vista as its ancestors and hence you can notice similar cues at points. On the contrary it is a lot better than Vista and have raised Tata's status that was experiencing a limbo for quite some time.