The main difference between the $message and $$message is given below:
| $message | $$message |
|---|---|
| $message is a regular variable. | $$message is a reference variable. |
| It has a fixed name and stores a fixed value. | It stores data about the variable. |
| Data stored in $message is fixed. | The value of the $$message can change dynamically as the value of the variable changes. |