It's a gradient, from the vector you mentioned all the way up to hash maps. And ordered maps fall somewhere in the middle. They might make sense if you're cre

It's a gradient, from the vector you mentioned all the way up to hash maps. And ordered maps fall somewhere in the middle. They might make sense if you're creating massive amounts of medium sized maps. Or if you need range searches etc. It's all compromises, there are no hard rules.