linkedhashmap vs linkedhashset code example

Example 1: hashmap vs linkedhashmap

Main difference between HashMap and LinkedHashMap
I remember is that LinkedHashMap maintains
insertion order of keys, 
On the other hand HashMap doesn't maintain
any order or keys or values.
Also LinkedHashMap requires more memory than HashMap
because of the ordering feature.
LinkedHashMap doublly Linked List to 
maintain order of elements.

Example 2: linkedhashmap vs linkedhashset

- LinkedHashSet can have null and keeps the order 
- LinkedHashMap can have only one null key, keeps order