What is the difference between ordered map and unordered map? asked 29 Jul '17, 14:01

One of them uses a redblack tree to sort out the map's keys such that searching for a key takes $O(log(N))$ in time complexity. The other one uses a hash to store the map's keys such that searching for a key takes $O(1)$ in time complexity. You know which is which ;) answered 29 Jul '17, 14:11

Answers to such questions can be simply googled.