In Spanish (as in Portuguese), estar is used for things that are transient in nature or potentially changeable; ser is used for things that are consistent or stable.
The only difference I can find is that in Spanish, estar is used for location, among many other things, but ser virtually never is. In Portuguese, both estar and ser are used, based on whether the location has a potential to be transient in nature.
For example, estar would be used for both the location of a house and a car, in Spanish. In Portuguese, estar would be used for a car and ser would be used for a house, since the location of the house cannot change.