Actually ViewStack and ViewState are not RELATED. View states give one way to change the look and feel of a component in RESPONSE to user action. We can also USE navigation container e.g. Acordion, ViewStack, Tab navigator etc. Choice of selecting navigation container or states depends upon requirement of application.

1. View stack is a component used to display different views (normally different data), one at a TIME. View states are related views of a single set of data. For example normal view and advanced view for a image.
2. In ViewStack components can not be shared easily between the different views, they had to be created each time view is changed. For example if we want a search box in every view, then it has to be created in every view. States work with transitions. We can apply various changes to a same component in various states. They will APPEAR according to states.

Actually ViewStack and ViewState are not related. View states give one way to change the look and feel of a component in response to user action. We can also use navigation container e.g. Acordion, ViewStack, Tab navigator etc. Choice of selecting navigation container or states depends upon requirement of application.