SortedList

one value per key 一键一值

SortedList

multiple values per key 一键多值

Lookup

SortedList与SortedDictionary

1)SortedList uses less memory than SortedDictionary.
2)SortedDictionary has faster insertion and removal of elements.
3)When populating the collection with already sorted data, SortedList is faster if capacity changes are not needed.