| Interface | Implements Set interface | Implements Map interface |
| Data Storage | Stores data as objects | Stores data as key-value pairs |
| Internal Structure | Uses HashMap internally | Uses an array of Entry<K, V> objects internally |
| Duplicate Elements | Doesn’t allow duplicates | Allows duplicate values but not duplicate keys |
| Null Elements | Allows only one null element | Allows one null key and multiple null values |
| Insertion Operation | Requires one object | Requires two objects – key and value |
| Performance | Slightly slower than HashMap | Slightly faster than HashSet |