Unordered Set and set

#1

Are these two stl’s used for hashing purpose? If no, then what is it’s application. If yes, then when to use it and when to use unordered map.
Please explain detailed difference between the two,

#2

map help you iterate over elements in a sorted way, therefore more time consuming.
unordered_map is just for hashing purposed , and doen’t sort a list.

#worst case search complexity.
For map, it is O( lg N )
For unordered_map, it is O( N ) [if hash function not good]
The same is applicable for worst case deletion complexity.